diff --git a/.github/workflows/git.yml b/.github/workflows/git.yml
index bbccaa36b..fef212763 100644
--- a/.github/workflows/git.yml
+++ b/.github/workflows/git.yml
@@ -16,7 +16,7 @@ jobs:
     - name: Install Go
       uses: actions/setup-go@v1
       with:
-        go-version: 1.14.x
+        go-version: 1.19.x
 
     - name: Checkout code
       uses: actions/checkout@v2
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 1644dcfc9..cefbbdf6e 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -5,7 +5,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        go-version: [1.15.x, 1.16.x]
+        go-version: [1.18.x, 1.19.x]
         platform: [ubuntu-latest, macos-latest, windows-latest]
     
     runs-on: ${{ matrix.platform }}
@@ -33,15 +33,16 @@ jobs:
       run: make test-coverage
 
     - name: Convert coverage to lcov
-      if: matrix.platform == 'ubuntu-latest' && matrix.go-version == '1.14.x' 
+      if: matrix.platform == 'ubuntu-latest' && matrix.go-version == '1.19.x' 
       uses: jandelgado/gcov2lcov-action@v1.0.0
       with:
           infile: coverage.out
           outfile: coverage.lcov
 
     - name: Coveralls
-      if: matrix.platform == 'ubuntu-latest' && matrix.go-version == '1.14.x' 
+      if: matrix.platform == 'ubuntu-latest' && matrix.go-version == '1.19.x' 
       uses: coverallsapp/github-action@master
+      continue-on-error: true
       with:
         github-token: ${{ secrets.GITHUB_TOKEN }}
         path-to-lcov: coverage.lcov
diff --git a/.gitignore b/.gitignore
index 038dd9f1e..e8d25f548 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@ coverage.out
 *~
 coverage.txt
 profile.out
+.tmp/
\ No newline at end of file
diff --git a/_examples/README.md b/_examples/README.md
index 92b9d4df4..3a4c539d0 100644
--- a/_examples/README.md
+++ b/_examples/README.md
@@ -19,6 +19,7 @@ Here you can find a list of annotated _go-git_ examples:
 - [branch](branch/main.go) - How to create and remove branches or any other kind of reference.
 - [tag](tag/main.go) - List/print repository tags.
 - [tag create and push](tag-create-push/main.go) - Create and push a new tag.
+- [tag find if head is tagged](find-if-any-tag-point-head/main.go) - Find if `HEAD` is tagged.
 - [remotes](remotes/main.go) - Working with remotes: adding, removing, etc.
 - [progress](progress/main.go) - Printing the progress information from the sideband.
 - [revision](revision/main.go) - Solve a revision into a commit.
diff --git a/_examples/azure_devops/main.go b/_examples/azure_devops/main.go
new file mode 100644
index 000000000..9c02ca080
--- /dev/null
+++ b/_examples/azure_devops/main.go
@@ -0,0 +1,56 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	git "github.com/go-git/go-git/v5"
+	. "github.com/go-git/go-git/v5/_examples"
+	"github.com/go-git/go-git/v5/plumbing/protocol/packp/capability"
+	"github.com/go-git/go-git/v5/plumbing/transport"
+	"github.com/go-git/go-git/v5/plumbing/transport/http"
+)
+
+func main() {
+	CheckArgs("<url>", "<directory>", "<azuredevops_username>", "<azuredevops_password>")
+	url, directory, username, password := os.Args[1], os.Args[2], os.Args[3], os.Args[4]
+
+	// Clone the given repository to the given directory
+	Info("git clone %s %s", url, directory)
+
+	// Azure DevOps requires capabilities multi_ack / multi_ack_detailed,
+	// which are not fully implemented and by default are included in
+	// transport.UnsupportedCapabilities.
+	//
+	// The initial clone operations require a full download of the repository,
+	// and therefore those unsupported capabilities are not as crucial, so
+	// by removing them from that list allows for the first clone to work
+	// successfully.
+	//
+	// Additional fetches will yield issues, therefore work always from a clean
+	// clone until those capabilities are fully supported.
+	//
+	// New commits and pushes against a remote worked without any issues.
+	transport.UnsupportedCapabilities = []capability.Capability{
+		capability.ThinPack,
+	}
+
+	r, err := git.PlainClone(directory, false, &git.CloneOptions{
+		Auth: &http.BasicAuth{
+			Username: username,
+			Password: password,
+		},
+		URL:      url,
+		Progress: os.Stdout,
+	})
+	CheckIfError(err)
+
+	// ... retrieving the branch being pointed by HEAD
+	ref, err := r.Head()
+	CheckIfError(err)
+	// ... retrieving the commit object
+	commit, err := r.CommitObject(ref.Hash())
+	CheckIfError(err)
+
+	fmt.Println(commit)
+}
diff --git a/_examples/find-if-any-tag-point-head/main.go b/_examples/find-if-any-tag-point-head/main.go
new file mode 100644
index 000000000..834aea2bb
--- /dev/null
+++ b/_examples/find-if-any-tag-point-head/main.go
@@ -0,0 +1,38 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/go-git/go-git/v5"
+	. "github.com/go-git/go-git/v5/_examples"
+	"github.com/go-git/go-git/v5/plumbing"
+)
+
+// Basic example of how to find if HEAD is tagged.
+func main() {
+	CheckArgs("<path>")
+	path := os.Args[1]
+
+	// We instantiate a new repository targeting the given path (the .git folder)
+	r, err := git.PlainOpen(path)
+	CheckIfError(err)
+
+	// Get HEAD reference to use for comparison later on.
+	ref, err := r.Head()
+	CheckIfError(err)
+
+	tags, err := r.Tags()
+	CheckIfError(err)
+
+	// List all tags, both lightweight tags and annotated tags and see if some tag points to HEAD reference.
+	err = tags.ForEach(func(t *plumbing.Reference) error {
+		// This technique should work for both lightweight and annotated tags.
+		revHash, err := r.ResolveRevision(plumbing.Revision(t.Name()))
+		CheckIfError(err)
+		if *revHash == ref.Hash() {
+			fmt.Printf("Found tag %s with hash %s pointing to HEAD %s\n", t.Name().Short(), revHash, ref.Hash())
+		}
+		return nil
+	})
+}
diff --git a/_examples/remotes/main.go b/_examples/remotes/main.go
index b1a91a9ef..d09957eae 100644
--- a/_examples/remotes/main.go
+++ b/_examples/remotes/main.go
@@ -33,7 +33,7 @@ func main() {
 	CheckIfError(err)
 
 	// List remotes from a repository
-	Info("git remotes -v")
+	Info("git remote -v")
 
 	list, err := r.Remotes()
 	CheckIfError(err)
diff --git a/common_test.go b/common_test.go
index 5f5bc4cd2..c0c4009e2 100644
--- a/common_test.go
+++ b/common_test.go
@@ -7,7 +7,6 @@ import (
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/plumbing/cache"
 	"github.com/go-git/go-git/v5/plumbing/format/packfile"
-	"github.com/go-git/go-git/v5/plumbing/transport"
 	"github.com/go-git/go-git/v5/storage/filesystem"
 	"github.com/go-git/go-git/v5/storage/memory"
 
@@ -25,8 +24,7 @@ type BaseSuite struct {
 	fixtures.Suite
 	Repository *Repository
 
-	backupProtocol transport.Transport
-	cache          map[string]*Repository
+	cache map[string]*Repository
 }
 
 func (s *BaseSuite) SetUpSuite(c *C) {
@@ -198,3 +196,11 @@ func AssertReferences(c *C, r *Repository, expected map[string]string) {
 		c.Assert(obtained, DeepEquals, expected)
 	}
 }
+
+func AssertReferencesMissing(c *C, r *Repository, expected []string) {
+	for _, name := range expected {
+		_, err := r.Reference(plumbing.ReferenceName(name), false)
+		c.Assert(err, NotNil)
+		c.Assert(err, Equals, plumbing.ErrReferenceNotFound)
+	}
+}
diff --git a/config/branch.go b/config/branch.go
index fe86cf542..652270a28 100644
--- a/config/branch.go
+++ b/config/branch.go
@@ -2,6 +2,7 @@ package config
 
 import (
 	"errors"
+	"strings"
 
 	"github.com/go-git/go-git/v5/plumbing"
 	format "github.com/go-git/go-git/v5/plumbing/format/config"
@@ -26,6 +27,12 @@ type Branch struct {
 	// "true" and "interactive".  "false" is undocumented and
 	// typically represented by the non-existence of this field
 	Rebase string
+	// Description explains what the branch is for.
+	// Multi-line explanations may be used.
+	//
+	// Original git command to edit:
+	//	git branch --edit-description
+	Description string
 
 	raw *format.Subsection
 }
@@ -75,9 +82,27 @@ func (b *Branch) marshal() *format.Subsection {
 		b.raw.SetOption(rebaseKey, b.Rebase)
 	}
 
+	if b.Description == "" {
+		b.raw.RemoveOption(descriptionKey)
+	} else {
+		desc := quoteDescription(b.Description)
+		b.raw.SetOption(descriptionKey, desc)
+	}
+
 	return b.raw
 }
 
+// hack to trigger conditional quoting in the
+// plumbing/format/config/Encoder.encodeOptions
+//
+// Current Encoder implementation uses Go %q format if value contains a backslash character,
+// which is not consistent with reference git implementation.
+// git just replaces newline characters with \n, while Encoder prints them directly.
+// Until value quoting fix, we should escape description value by replacing newline characters with \n.
+func quoteDescription(desc string) string {
+	return strings.ReplaceAll(desc, "\n", `\n`)
+}
+
 func (b *Branch) unmarshal(s *format.Subsection) error {
 	b.raw = s
 
@@ -85,6 +110,14 @@ func (b *Branch) unmarshal(s *format.Subsection) error {
 	b.Remote = b.raw.Options.Get(remoteSection)
 	b.Merge = plumbing.ReferenceName(b.raw.Options.Get(mergeKey))
 	b.Rebase = b.raw.Options.Get(rebaseKey)
+	b.Description = unquoteDescription(b.raw.Options.Get(descriptionKey))
 
 	return b.Validate()
 }
+
+// hack to enable conditional quoting in the
+// plumbing/format/config/Encoder.encodeOptions
+// goto quoteDescription for details.
+func unquoteDescription(desc string) string {
+	return strings.ReplaceAll(desc, `\n`, "\n")
+}
diff --git a/config/config.go b/config/config.go
index 1aee25a4c..8051bc145 100644
--- a/config/config.go
+++ b/config/config.go
@@ -15,7 +15,6 @@ import (
 	"github.com/go-git/go-billy/v5/osfs"
 	"github.com/go-git/go-git/v5/internal/url"
 	format "github.com/go-git/go-git/v5/plumbing/format/config"
-	"github.com/mitchellh/go-homedir"
 )
 
 const (
@@ -150,7 +149,7 @@ func ReadConfig(r io.Reader) (*Config, error) {
 // config file to the given scope, a empty one is returned.
 func LoadConfig(scope Scope) (*Config, error) {
 	if scope == LocalScope {
-		return nil, fmt.Errorf("LocalScope should be read from the a ConfigStorer.")
+		return nil, fmt.Errorf("LocalScope should be read from the a ConfigStorer")
 	}
 
 	files, err := Paths(scope)
@@ -185,7 +184,7 @@ func Paths(scope Scope) ([]string, error) {
 			files = append(files, filepath.Join(xdg, "git/config"))
 		}
 
-		home, err := homedir.Dir()
+		home, err := os.UserHomeDir()
 		if err != nil {
 			return nil, err
 		}
@@ -247,6 +246,7 @@ const (
 	rebaseKey        = "rebase"
 	nameKey          = "name"
 	emailKey         = "email"
+	descriptionKey   = "description"
 	defaultBranchKey = "defaultBranch"
 
 	// DefaultPackWindow holds the number of previous objects used to
diff --git a/config/config_test.go b/config/config_test.go
index 6f0242d96..7e9483f6f 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -50,6 +50,7 @@ func (s *ConfigSuite) TestUnmarshal(c *C) {
 [branch "master"]
 		remote = origin
 		merge = refs/heads/master
+		description = "Add support for branch description.\\n\\nEdit branch description: git branch --edit-description\\n"
 [init]
 		defaultBranch = main
 [url "ssh://git@github.com/"]
@@ -86,6 +87,7 @@ func (s *ConfigSuite) TestUnmarshal(c *C) {
 	c.Assert(cfg.Submodules["qux"].Branch, Equals, "bar")
 	c.Assert(cfg.Branches["master"].Remote, Equals, "origin")
 	c.Assert(cfg.Branches["master"].Merge, Equals, plumbing.ReferenceName("refs/heads/master"))
+	c.Assert(cfg.Branches["master"].Description, Equals, "Add support for branch description.\n\nEdit branch description: git branch --edit-description\n")
 	c.Assert(cfg.Init.DefaultBranch, Equals, "main")
 }
 
@@ -111,6 +113,7 @@ func (s *ConfigSuite) TestMarshal(c *C) {
 [branch "master"]
 	remote = origin
 	merge = refs/heads/master
+	description = "Add support for branch description.\\n\\nEdit branch description: git branch --edit-description\\n"
 [url "ssh://git@github.com/"]
 	insteadOf = https://github.com/
 [init]
@@ -149,9 +152,10 @@ func (s *ConfigSuite) TestMarshal(c *C) {
 	}
 
 	cfg.Branches["master"] = &Branch{
-		Name:   "master",
-		Remote: "origin",
-		Merge:  "refs/heads/master",
+		Name:        "master",
+		Remote:      "origin",
+		Merge:       "refs/heads/master",
+		Description: "Add support for branch description.\n\nEdit branch description: git branch --edit-description\n",
 	}
 
 	cfg.URLs["ssh://git@github.com/"] = &URL{
@@ -361,7 +365,9 @@ func (s *ConfigSuite) TestRemoveUrlOptions(c *C) {
 	cfg.Remotes["alt"].URLs = []string{}
 
 	buf, err = cfg.Marshal()
+	c.Assert(err, IsNil)
 	if strings.Contains(string(buf), "url") {
 		c.Fatal("conifg should not contain any url sections")
 	}
+	c.Assert(err, IsNil)
 }
diff --git a/config/refspec.go b/config/refspec.go
index 4bfaa37bb..e2cf8c97b 100644
--- a/config/refspec.go
+++ b/config/refspec.go
@@ -64,7 +64,7 @@ func (s RefSpec) IsExactSHA1() bool {
 	return plumbing.IsHash(s.Src())
 }
 
-// Src return the src side.
+// Src returns the src side.
 func (s RefSpec) Src() string {
 	spec := string(s)
 
diff --git a/go.mod b/go.mod
index 402613f0f..b214c8a8d 100644
--- a/go.mod
+++ b/go.mod
@@ -1,29 +1,28 @@
 module github.com/go-git/go-git/v5
 
 require (
-	github.com/Microsoft/go-winio v0.4.16 // indirect
-	github.com/ProtonMail/go-crypto v0.0.0-20210428141323-04723f9f07d7
+	github.com/ProtonMail/go-crypto v0.0.0-20221026131551-cf6655e29de4
 	github.com/acomagu/bufpipe v1.0.3
-	github.com/anmitsu/go-shlex v0.0.0-20161002113705-648efa622239 // indirect
 	github.com/armon/go-socks5 v0.0.0-20160902184237-e75332964ef5
-	github.com/emirpasic/gods v1.12.0
-	github.com/flynn/go-shlex v0.0.0-20150515145356-3f9db97f8568 // indirect
-	github.com/gliderlabs/ssh v0.2.2
+	github.com/emirpasic/gods v1.18.1
+	github.com/gliderlabs/ssh v0.3.5
 	github.com/go-git/gcfg v1.5.0
 	github.com/go-git/go-billy/v5 v5.3.1
-	github.com/go-git/go-git-fixtures/v4 v4.2.1
-	github.com/google/go-cmp v0.3.0
-	github.com/imdario/mergo v0.3.12
+	github.com/go-git/go-git-fixtures/v4 v4.3.1
+	github.com/google/go-cmp v0.5.9
+	github.com/imdario/mergo v0.3.13
 	github.com/jbenet/go-context v0.0.0-20150711004518-d14ea06fba99
 	github.com/jessevdk/go-flags v1.5.0
-	github.com/kevinburke/ssh_config v0.0.0-20201106050909-4977a11b4351
-	github.com/mitchellh/go-homedir v1.1.0
+	github.com/kevinburke/ssh_config v1.2.0
+	github.com/pjbgf/sha1cd v0.2.0
+	github.com/pkg/errors v0.9.1 // indirect
 	github.com/sergi/go-diff v1.1.0
-	github.com/xanzy/ssh-agent v0.3.0
-	golang.org/x/crypto v0.0.0-20210421170649-83a5a9bb288b
-	golang.org/x/net v0.0.0-20210326060303-6b1517762897
-	golang.org/x/sys v0.0.0-20210502180810-71e4cd670f79
-	golang.org/x/text v0.3.3
+	github.com/skeema/knownhosts v1.1.0
+	github.com/xanzy/ssh-agent v0.3.2
+	golang.org/x/crypto v0.3.0
+	golang.org/x/net v0.2.0
+	golang.org/x/sys v0.2.0
+	golang.org/x/text v0.4.0
 	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c
 	gopkg.in/warnings.v0 v0.1.2 // indirect
 )
diff --git a/go.sum b/go.sum
index 922724775..2c00f0092 100644
--- a/go.sum
+++ b/go.sum
@@ -1,44 +1,40 @@
-github.com/Microsoft/go-winio v0.4.14/go.mod h1:qXqCSQ3Xa7+6tgxaGTIe4Kpcdsi+P8jBhyzoq1bpyYA=
-github.com/Microsoft/go-winio v0.4.16 h1:FtSW/jqD+l4ba5iPBj9CODVtgfYAD8w2wS923g/cFDk=
-github.com/Microsoft/go-winio v0.4.16/go.mod h1:XB6nPKklQyQ7GC9LdcBEcBl8PF76WugXOPRXwdLnMv0=
-github.com/ProtonMail/go-crypto v0.0.0-20210428141323-04723f9f07d7 h1:YoJbenK9C67SkzkDfmQuVln04ygHj3vjZfd9FL+GmQQ=
-github.com/ProtonMail/go-crypto v0.0.0-20210428141323-04723f9f07d7/go.mod h1:z4/9nQmJSSwwds7ejkxaJwO37dru3geImFUdJlaLzQo=
+github.com/Microsoft/go-winio v0.5.2 h1:a9IhgEQBCUEk6QCdml9CiJGhAws+YwffDHEMp1VMrpA=
+github.com/Microsoft/go-winio v0.5.2/go.mod h1:WpS1mjBmmwHBEWmogvA2mj8546UReBk4v8QkMxJ6pZY=
+github.com/ProtonMail/go-crypto v0.0.0-20221026131551-cf6655e29de4 h1:ra2OtmuW0AE5csawV4YXMNGNQQXvLRps3z2Z59OPO+I=
+github.com/ProtonMail/go-crypto v0.0.0-20221026131551-cf6655e29de4/go.mod h1:UBYPn8k0D56RtnR8RFQMjmh4KrZzWJ5o7Z9SYjossQ8=
 github.com/acomagu/bufpipe v1.0.3 h1:fxAGrHZTgQ9w5QqVItgzwj235/uYZYgbXitB+dLupOk=
 github.com/acomagu/bufpipe v1.0.3/go.mod h1:mxdxdup/WdsKVreO5GpW4+M/1CE2sMG4jeGJ2sYmHc4=
-github.com/anmitsu/go-shlex v0.0.0-20161002113705-648efa622239 h1:kFOfPq6dUM1hTo4JG6LR5AXSUEsOjtdm0kw0FtQtMJA=
-github.com/anmitsu/go-shlex v0.0.0-20161002113705-648efa622239/go.mod h1:2FmKhYUyUczH0OGQWaF5ceTx0UBShxjsH6f8oGKYe2c=
+github.com/anmitsu/go-shlex v0.0.0-20200514113438-38f4b401e2be h1:9AeTilPcZAjCFIImctFaOjnTIavg87rW78vTPkQqLI8=
+github.com/anmitsu/go-shlex v0.0.0-20200514113438-38f4b401e2be/go.mod h1:ySMOLuWl6zY27l47sB3qLNK6tF2fkHG55UZxx8oIVo4=
 github.com/armon/go-socks5 v0.0.0-20160902184237-e75332964ef5 h1:0CwZNZbxp69SHPdPJAN/hZIm0C4OItdklCFmMRWYpio=
 github.com/armon/go-socks5 v0.0.0-20160902184237-e75332964ef5/go.mod h1:wHh0iHkYZB8zMSxRWpUBQtwG5a7fFgvEO+odwuTv2gs=
+github.com/bwesterb/go-ristretto v1.2.0/go.mod h1:fUIoIZaG73pV5biE2Blr2xEzDoMj7NFEuV9ekS419A0=
+github.com/cloudflare/circl v1.1.0 h1:bZgT/A+cikZnKIwn7xL2OBj012Bmvho/o6RpRvv3GKY=
+github.com/cloudflare/circl v1.1.0/go.mod h1:prBCrKB9DV4poKZY1l9zBXg2QJY7mvgRvtMxxK7fi4I=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/emirpasic/gods v1.12.0 h1:QAUIPSaCu4G+POclxeqb3F+WPpdKqFGlw36+yOzGlrg=
-github.com/emirpasic/gods v1.12.0/go.mod h1:YfzfFFoVP/catgzJb4IKIqXjX78Ha8FMSDh3ymbK86o=
-github.com/flynn/go-shlex v0.0.0-20150515145356-3f9db97f8568 h1:BHsljHzVlRcyQhjrss6TZTdY2VfCqZPbv5k3iBFa2ZQ=
-github.com/flynn/go-shlex v0.0.0-20150515145356-3f9db97f8568/go.mod h1:xEzjJPgXI435gkrCt3MPfRiAkVrwSbHsst4LCFVfpJc=
-github.com/gliderlabs/ssh v0.2.2 h1:6zsha5zo/TWhRhwqCD3+EarCAgZ2yN28ipRnGPnwkI0=
-github.com/gliderlabs/ssh v0.2.2/go.mod h1:U7qILu1NlMHj9FlMhZLlkCdDnU1DBEAqr0aevW3Awn0=
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+golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
@@ -97,7 +121,6 @@ gopkg.in/warnings.v0 v0.1.2 h1:wFXVbFY8DY5/xOe1ECiWdKCzZlxgshcYVNkBHstARME=
 gopkg.in/warnings.v0 v0.1.2/go.mod h1:jksf8JmL6Qr/oQM2OXTHunEvvTAsrWBLb6OOjuVWRNI=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.4/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
-gopkg.in/yaml.v2 v2.3.0 h1:clyUAQHOM3G0M3f5vQj7LuJrETvjVot3Z5el9nffUtU=
-gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.0 h1:hjy8E9ON/egN1tAYqKb61G10WtihqetD4sz2H+8nIeA=
+gopkg.in/yaml.v3 v3.0.0/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/internal/revision/parser.go b/internal/revision/parser.go
index 8facf17ff..8a2a7190e 100644
--- a/internal/revision/parser.go
+++ b/internal/revision/parser.go
@@ -322,6 +322,8 @@ func (p *Parser) parseAt() (Revisioner, error) {
 				}
 
 				return AtDate{t}, nil
+			case tok == eof:
+				return nil, &ErrInvalidRevision{s: `missing "}" in @{<data>} structure`}
 			default:
 				date += lit
 			}
@@ -424,6 +426,8 @@ func (p *Parser) parseCaretBraces() (Revisioner, error) {
 			p.unscan()
 		case tok != slash && start:
 			return nil, &ErrInvalidRevision{fmt.Sprintf(`"%s" is not a valid revision suffix brace component`, lit)}
+		case tok == eof:
+			return nil, &ErrInvalidRevision{s: `missing "}" in ^{<data>} structure`}
 		case tok != cbrace:
 			p.unscan()
 			re += lit
diff --git a/internal/revision/parser_test.go b/internal/revision/parser_test.go
index 98403cc23..3a77b2f11 100644
--- a/internal/revision/parser_test.go
+++ b/internal/revision/parser_test.go
@@ -183,7 +183,7 @@ func (s *ParserSuite) TestParseWithValidExpression(c *C) {
 	}
 }
 
-func (s *ParserSuite) TestParseWithUnValidExpression(c *C) {
+func (s *ParserSuite) TestParseWithInvalidExpression(c *C) {
 	datas := map[string]error{
 		"..":                              &ErrInvalidRevision{`must not start with "."`},
 		"master^1master":                  &ErrInvalidRevision{`reference must be defined once at the beginning`},
@@ -198,6 +198,9 @@ func (s *ParserSuite) TestParseWithUnValidExpression(c *C) {
 		"~1":                              &ErrInvalidRevision{`"~" or "^" statement must have a reference defined at the beginning`},
 		"master:/test":                    &ErrInvalidRevision{`":" statement is not valid, could be : :/<regexp>`},
 		"master:0:README":                 &ErrInvalidRevision{`":" statement is not valid, could be : :<n>:<path>`},
+		"^{/":                             &ErrInvalidRevision{`missing "}" in ^{<data>} structure`},
+		"~@{":                             &ErrInvalidRevision{`missing "}" in @{<data>} structure`},
+		"@@{{0":                           &ErrInvalidRevision{`missing "}" in @{<data>} structure`},
 	}
 
 	for s, e := range datas {
@@ -230,7 +233,7 @@ func (s *ParserSuite) TestParseAtWithValidExpression(c *C) {
 	}
 }
 
-func (s *ParserSuite) TestParseAtWithUnValidExpression(c *C) {
+func (s *ParserSuite) TestParseAtWithInvalidExpression(c *C) {
 	datas := map[string]error{
 		"{test}": &ErrInvalidRevision{`wrong date "test" must fit ISO-8601 format : 2006-01-02T15:04:05Z`},
 		"{-1":    &ErrInvalidRevision{`missing "}" in @{-n} structure`},
diff --git a/object_walker.go b/object_walker.go
index 3fcdd2999..3a537bd80 100644
--- a/object_walker.go
+++ b/object_walker.go
@@ -60,7 +60,7 @@ func (p *objectWalker) walkObjectTree(hash plumbing.Hash) error {
 	// Fetch the object.
 	obj, err := object.GetObject(p.Storer, hash)
 	if err != nil {
-		return fmt.Errorf("Getting object %s failed: %v", hash, err)
+		return fmt.Errorf("getting object %s failed: %v", hash, err)
 	}
 	// Walk all children depending on object type.
 	switch obj := obj.(type) {
@@ -98,7 +98,7 @@ func (p *objectWalker) walkObjectTree(hash plumbing.Hash) error {
 		return p.walkObjectTree(obj.Target)
 	default:
 		// Error out on unhandled object types.
-		return fmt.Errorf("Unknown object %X %s %T\n", obj.ID(), obj.Type(), obj)
+		return fmt.Errorf("unknown object %X %s %T", obj.ID(), obj.Type(), obj)
 	}
 	return nil
 }
diff --git a/options.go b/options.go
index 70687965b..7e5c1b434 100644
--- a/options.go
+++ b/options.go
@@ -91,6 +91,8 @@ func (o *CloneOptions) Validate() error {
 type PullOptions struct {
 	// Name of the remote to be pulled. If empty, uses the default.
 	RemoteName string
+	// RemoteURL overrides the remote repo address with a custom URL
+	RemoteURL string
 	// Remote branch to clone. If empty, uses HEAD.
 	ReferenceName plumbing.ReferenceName
 	// Fetch only ReferenceName if true.
@@ -147,7 +149,9 @@ const (
 type FetchOptions struct {
 	// Name of the remote to fetch from. Defaults to origin.
 	RemoteName string
-	RefSpecs   []config.RefSpec
+	// RemoteURL overrides the remote repo address with a custom URL
+	RemoteURL string
+	RefSpecs  []config.RefSpec
 	// Depth limit fetching to the specified number of commits from the tip of
 	// each remote branch history.
 	Depth int
@@ -192,8 +196,16 @@ func (o *FetchOptions) Validate() error {
 type PushOptions struct {
 	// RemoteName is the name of the remote to be pushed to.
 	RemoteName string
-	// RefSpecs specify what destination ref to update with what source
-	// object. A refspec with empty src can be used to delete a reference.
+	// RemoteURL overrides the remote repo address with a custom URL
+	RemoteURL string
+	// RefSpecs specify what destination ref to update with what source object.
+	//
+	// The format of a <refspec> parameter is an optional plus +, followed by
+	//  the source object <src>, followed by a colon :, followed by the destination ref <dst>.
+	// The <src> is often the name of the branch you would want to push, but it can be a SHA-1.
+	// The <dst> tells which ref on the remote side is updated with this push.
+	//
+	// A refspec with empty src can be used to delete a reference.
 	RefSpecs []config.RefSpec
 	// Auth credentials, if required, to use with the remote repository.
 	Auth transport.AuthMethod
@@ -206,13 +218,35 @@ type PushOptions struct {
 	// Force allows the push to update a remote branch even when the local
 	// branch does not descend from it.
 	Force bool
-	// InsecureSkipTLS skips ssl verify if protocal is https
+	// InsecureSkipTLS skips ssl verify if protocol is https
 	InsecureSkipTLS bool
 	// CABundle specify additional ca bundle with system cert pool
 	CABundle []byte
 	// RequireRemoteRefs only allows a remote ref to be updated if its current
 	// value is the one specified here.
 	RequireRemoteRefs []config.RefSpec
+	// FollowTags will send any annotated tags with a commit target reachable from
+	// the refs already being pushed
+	FollowTags bool
+	// ForceWithLease allows a force push as long as the remote ref adheres to a "lease"
+	ForceWithLease *ForceWithLease
+	// PushOptions sets options to be transferred to the server during push.
+	Options map[string]string
+	// Atomic sets option to be an atomic push
+	Atomic bool
+}
+
+// ForceWithLease sets fields on the lease
+// If neither RefName nor Hash are set, ForceWithLease protects
+// all refs in the refspec by ensuring the ref of the remote in the local repsitory
+// matches the one in the ref advertisement.
+type ForceWithLease struct {
+	// RefName, when set will protect the ref by ensuring it matches the
+	// hash in the ref advertisement.
+	RefName plumbing.ReferenceName
+	// Hash is the expected object id of RefName. The push will be rejected unless this
+	// matches the corresponding object id of RefName in the refs advertisement.
+	Hash plumbing.Hash
 }
 
 // Validate validates the fields and sets the default values.
@@ -274,6 +308,8 @@ type CheckoutOptions struct {
 	// target branch. Force and Keep are mutually exclusive, should not be both
 	// set to true.
 	Keep bool
+	// SparseCheckoutDirectories
+	SparseCheckoutDirectories []string
 }
 
 // Validate validates the fields and sets the default values.
@@ -366,7 +402,7 @@ type LogOptions struct {
 
 	// Show only those commits in which the specified file was inserted/updated.
 	// It is equivalent to running `git log -- <file-name>`.
-	// this field is kept for compatility, it can be replaced with PathFilter
+	// this field is kept for compatibility, it can be replaced with PathFilter
 	FileName *string
 
 	// Filter commits based on the path of files that are updated
@@ -571,7 +607,7 @@ func (o *CreateTagOptions) loadConfigTagger(r *Repository) error {
 type ListOptions struct {
 	// Auth credentials, if required, to use with the remote repository.
 	Auth transport.AuthMethod
-	// InsecureSkipTLS skips ssl verify if protocal is https
+	// InsecureSkipTLS skips ssl verify if protocol is https
 	InsecureSkipTLS bool
 	// CABundle specify additional ca bundle with system cert pool
 	CABundle []byte
diff --git a/plumbing/format/commitgraph/encoder.go b/plumbing/format/commitgraph/encoder.go
index d34076fc3..bcf7d030a 100644
--- a/plumbing/format/commitgraph/encoder.go
+++ b/plumbing/format/commitgraph/encoder.go
@@ -1,11 +1,11 @@
 package commitgraph
 
 import (
-	"crypto/sha1"
-	"hash"
+	"crypto"
 	"io"
 
 	"github.com/go-git/go-git/v5/plumbing"
+	"github.com/go-git/go-git/v5/plumbing/hash"
 	"github.com/go-git/go-git/v5/utils/binary"
 )
 
@@ -17,7 +17,7 @@ type Encoder struct {
 
 // NewEncoder returns a new stream encoder that writes to w.
 func NewEncoder(w io.Writer) *Encoder {
-	h := sha1.New()
+	h := hash.New(crypto.SHA1)
 	mw := io.MultiWriter(w, h)
 	return &Encoder{mw, h}
 }
diff --git a/plumbing/format/commitgraph/file.go b/plumbing/format/commitgraph/file.go
index 0ce719823..1d25238f5 100644
--- a/plumbing/format/commitgraph/file.go
+++ b/plumbing/format/commitgraph/file.go
@@ -14,14 +14,14 @@ import (
 var (
 	// ErrUnsupportedVersion is returned by OpenFileIndex when the commit graph
 	// file version is not supported.
-	ErrUnsupportedVersion = errors.New("Unsupported version")
+	ErrUnsupportedVersion = errors.New("unsupported version")
 	// ErrUnsupportedHash is returned by OpenFileIndex when the commit graph
 	// hash function is not supported. Currently only SHA-1 is defined and
 	// supported
-	ErrUnsupportedHash = errors.New("Unsupported hash algorithm")
+	ErrUnsupportedHash = errors.New("unsupported hash algorithm")
 	// ErrMalformedCommitGraphFile is returned by OpenFileIndex when the commit
 	// graph file is corrupted.
-	ErrMalformedCommitGraphFile = errors.New("Malformed commit graph file")
+	ErrMalformedCommitGraphFile = errors.New("malformed commit graph file")
 
 	commitFileSignature    = []byte{'C', 'G', 'P', 'H'}
 	oidFanoutSignature     = []byte{'O', 'I', 'D', 'F'}
diff --git a/plumbing/format/config/encoder.go b/plumbing/format/config/encoder.go
index 4eac8968a..de069aed5 100644
--- a/plumbing/format/config/encoder.go
+++ b/plumbing/format/config/encoder.go
@@ -11,6 +11,10 @@ type Encoder struct {
 	w io.Writer
 }
 
+var (
+	subsectionReplacer = strings.NewReplacer(`"`, `\"`, `\`, `\\`)
+	valueReplacer = strings.NewReplacer(`"`, `\"`, `\`, `\\`, "\n", `\n`, "\t", `\t`, "\b", `\b`)
+)
 // NewEncoder returns a new encoder that writes to w.
 func NewEncoder(w io.Writer) *Encoder {
 	return &Encoder{w}
@@ -48,8 +52,7 @@ func (e *Encoder) encodeSection(s *Section) error {
 }
 
 func (e *Encoder) encodeSubsection(sectionName string, s *Subsection) error {
-	//TODO: escape
-	if err := e.printf("[%s \"%s\"]\n", sectionName, s.Name); err != nil {
+	if err := e.printf("[%s \"%s\"]\n", sectionName, subsectionReplacer.Replace(s.Name)); err != nil {
 		return err
 	}
 
@@ -58,12 +61,14 @@ func (e *Encoder) encodeSubsection(sectionName string, s *Subsection) error {
 
 func (e *Encoder) encodeOptions(opts Options) error {
 	for _, o := range opts {
-		pattern := "\t%s = %s\n"
-		if strings.Contains(o.Value, "\\") {
-			pattern = "\t%s = %q\n"
+		var value string
+		if strings.ContainsAny(o.Value, "#;\"\t\n\\") || strings.HasPrefix(o.Value, " ") || strings.HasSuffix(o.Value, " ") {
+			value = `"`+valueReplacer.Replace(o.Value)+`"`
+		} else {
+			value = o.Value
 		}
 
-		if err := e.printf(pattern, o.Key, o.Value); err != nil {
+		if err := e.printf("\t%s = %s\n", o.Key, value); err != nil {
 			return err
 		}
 	}
diff --git a/plumbing/format/config/fixtures_test.go b/plumbing/format/config/fixtures_test.go
index f3533dfee..2fa7840b0 100644
--- a/plumbing/format/config/fixtures_test.go
+++ b/plumbing/format/config/fixtures_test.go
@@ -42,6 +42,41 @@ var fixtures = []*Fixture{
 		Text:   "[core]\n\trepositoryformatversion = 0\n",
 		Config: New().AddOption("core", "", "repositoryformatversion", "0"),
 	},
+	{
+		Raw: `[section]
+	option1 = "has # hash"
+	option2 = "has \" quote"
+	option3 = "has \\ backslash"
+	option4 = "has ; semicolon"
+	option5 = "has \n line-feed"
+	option6 = "has \t tab"
+	option7 = "  has leading spaces"
+	option8 = "has trailing spaces  "
+	option9 = has no special characters
+	option10 = has unusual ` + "\x01\x7f\xc8\x80 characters\n",
+		Text: `[section]
+	option1 = "has # hash"
+	option2 = "has \" quote"
+	option3 = "has \\ backslash"
+	option4 = "has ; semicolon"
+	option5 = "has \n line-feed"
+	option6 = "has \t tab"
+	option7 = "  has leading spaces"
+	option8 = "has trailing spaces  "
+	option9 = has no special characters
+	option10 = has unusual ` + "\x01\x7f\xc8\x80 characters\n",
+		Config: New().
+			AddOption("section", "", "option1", `has # hash`).
+			AddOption("section", "", "option2", `has " quote`).
+			AddOption("section", "", "option3", `has \ backslash`).
+			AddOption("section", "", "option4", `has ; semicolon`).
+			AddOption("section", "", "option5", "has \n line-feed").
+			AddOption("section", "", "option6", "has \t tab").
+			AddOption("section", "", "option7", `  has leading spaces`).
+			AddOption("section", "", "option8", `has trailing spaces  `).
+			AddOption("section", "", "option9", `has no special characters`).
+			AddOption("section", "", "option10", "has unusual \x01\x7f\u0200 characters"),
+	},
 	{
 		Raw: `
 			[sect1]
diff --git a/plumbing/format/config/section.go b/plumbing/format/config/section.go
index 07f72f35a..4625ac583 100644
--- a/plumbing/format/config/section.go
+++ b/plumbing/format/config/section.go
@@ -103,7 +103,7 @@ func (s *Section) RemoveSubsection(name string) *Section {
 	return s
 }
 
-// Option return the value for the specified key. Empty string is returned if
+// Option returns the value for the specified key. Empty string is returned if
 // key does not exists.
 func (s *Section) Option(key string) string {
 	return s.Options.Get(key)
diff --git a/plumbing/format/diff/patch.go b/plumbing/format/diff/patch.go
index 39a66a1a8..c7678b01a 100644
--- a/plumbing/format/diff/patch.go
+++ b/plumbing/format/diff/patch.go
@@ -9,7 +9,7 @@ import (
 type Operation int
 
 const (
-	// Equal item represents a equals diff.
+	// Equal item represents an equals diff.
 	Equal Operation = iota
 	// Add item represents an insert diff.
 	Add
@@ -26,15 +26,15 @@ type Patch interface {
 	Message() string
 }
 
-// FilePatch represents the necessary steps to transform one file to another.
+// FilePatch represents the necessary steps to transform one file into another.
 type FilePatch interface {
 	// IsBinary returns true if this patch is representing a binary file.
 	IsBinary() bool
-	// Files returns the from and to Files, with all the necessary metadata to
+	// Files returns the from and to Files, with all the necessary metadata
 	// about them. If the patch creates a new file, "from" will be nil.
 	// If the patch deletes a file, "to" will be nil.
 	Files() (from, to File)
-	// Chunks returns a slice of ordered changes to transform "from" File to
+	// Chunks returns a slice of ordered changes to transform "from" File into
 	// "to" File. If the file is a binary one, Chunks will be empty.
 	Chunks() []Chunk
 }
@@ -49,7 +49,7 @@ type File interface {
 	Path() string
 }
 
-// Chunk represents a portion of a file transformation to another.
+// Chunk represents a portion of a file transformation into another.
 type Chunk interface {
 	// Content contains the portion of the file.
 	Content() string
diff --git a/plumbing/format/gitattributes/attributes.go b/plumbing/format/gitattributes/attributes.go
index d13c2a903..329e66731 100644
--- a/plumbing/format/gitattributes/attributes.go
+++ b/plumbing/format/gitattributes/attributes.go
@@ -15,7 +15,7 @@ const (
 
 var (
 	ErrMacroNotAllowed      = errors.New("macro not allowed")
-	ErrInvalidAttributeName = errors.New("Invalid attribute name")
+	ErrInvalidAttributeName = errors.New("invalid attribute name")
 )
 
 type MatchAttribute struct {
diff --git a/plumbing/format/gitattributes/pattern.go b/plumbing/format/gitattributes/pattern.go
index d961aba9c..f101f4725 100644
--- a/plumbing/format/gitattributes/pattern.go
+++ b/plumbing/format/gitattributes/pattern.go
@@ -52,6 +52,11 @@ func (p *pattern) Match(path []string) bool {
 	var match, doublestar bool
 	var err error
 	for _, part := range path {
+		// path is deeper than pattern
+		if len(pattern) == 0 {
+			return false
+		}
+
 		// skip empty
 		if pattern[0] == "" {
 			pattern = pattern[1:]
diff --git a/plumbing/format/gitattributes/pattern_test.go b/plumbing/format/gitattributes/pattern_test.go
index f95be6e7e..981d56f56 100644
--- a/plumbing/format/gitattributes/pattern_test.go
+++ b/plumbing/format/gitattributes/pattern_test.go
@@ -174,6 +174,12 @@ func (s *PatternSuite) TestGlobMatch_tailingAsterisks_single(c *C) {
 	c.Assert(r, Equals, true)
 }
 
+func (s *PatternSuite) TestGlobMatch_tailingAsterisk_single(c *C) {
+	p := ParsePattern("/*lue/*", nil)
+	r := p.Match([]string{"value", "volcano", "tail"})
+	c.Assert(r, Equals, false)
+}
+
 func (s *PatternSuite) TestGlobMatch_tailingAsterisks_exactMatch(c *C) {
 	p := ParsePattern("/*lue/vol?ano/**", nil)
 	r := p.Match([]string{"value", "volcano"})
diff --git a/plumbing/format/gitignore/dir.go b/plumbing/format/gitignore/dir.go
index 7cea50cd8..15bc9c779 100644
--- a/plumbing/format/gitignore/dir.go
+++ b/plumbing/format/gitignore/dir.go
@@ -13,13 +13,14 @@ import (
 )
 
 const (
-	commentPrefix = "#"
-	coreSection   = "core"
-	excludesfile  = "excludesfile"
-	gitDir        = ".git"
-	gitignoreFile = ".gitignore"
-	gitconfigFile = ".gitconfig"
-	systemFile    = "/etc/gitconfig"
+	commentPrefix   = "#"
+	coreSection     = "core"
+	excludesfile    = "excludesfile"
+	gitDir          = ".git"
+	gitignoreFile   = ".gitignore"
+	gitconfigFile   = ".gitconfig"
+	systemFile      = "/etc/gitconfig"
+	infoExcludeFile = gitDir + "/info/exclude"
 )
 
 // readIgnoreFile reads a specific git ignore file.
@@ -42,10 +43,14 @@ func readIgnoreFile(fs billy.Filesystem, path []string, ignoreFile string) (ps [
 	return
 }
 
-// ReadPatterns reads gitignore patterns recursively traversing through the directory
-// structure. The result is in the ascending order of priority (last higher).
+// ReadPatterns reads the .git/info/exclude and then the gitignore patterns
+// recursively traversing through the directory structure. The result is in
+// the ascending order of priority (last higher).
 func ReadPatterns(fs billy.Filesystem, path []string) (ps []Pattern, err error) {
-	ps, _ = readIgnoreFile(fs, path, gitignoreFile)
+	ps, _ = readIgnoreFile(fs, path, infoExcludeFile)
+
+	subps, _ := readIgnoreFile(fs, path, gitignoreFile)
+	ps = append(ps, subps...)
 
 	var fis []os.FileInfo
 	fis, err = fs.ReadDir(fs.Join(path...))
diff --git a/plumbing/format/gitignore/dir_test.go b/plumbing/format/gitignore/dir_test.go
index 94ed7befc..facc36d8e 100644
--- a/plumbing/format/gitignore/dir_test.go
+++ b/plumbing/format/gitignore/dir_test.go
@@ -24,7 +24,17 @@ var _ = Suite(&MatcherSuite{})
 func (s *MatcherSuite) SetUpTest(c *C) {
 	// setup generic git repository root
 	fs := memfs.New()
-	f, err := fs.Create(".gitignore")
+
+	err := fs.MkdirAll(".git/info", os.ModePerm)
+	c.Assert(err, IsNil)
+	f, err := fs.Create(".git/info/exclude")
+	c.Assert(err, IsNil)
+	_, err = f.Write([]byte("exclude.crlf\r\n"))
+	c.Assert(err, IsNil)
+	err = f.Close()
+	c.Assert(err, IsNil)
+
+	f, err = fs.Create(".gitignore")
 	c.Assert(err, IsNil)
 	_, err = f.Write([]byte("vendor/g*/\n"))
 	c.Assert(err, IsNil)
@@ -44,6 +54,8 @@ func (s *MatcherSuite) SetUpTest(c *C) {
 
 	err = fs.MkdirAll("another", os.ModePerm)
 	c.Assert(err, IsNil)
+	err = fs.MkdirAll("exclude.crlf", os.ModePerm)
+	c.Assert(err, IsNil)
 	err = fs.MkdirAll("ignore.crlf", os.ModePerm)
 	c.Assert(err, IsNil)
 	err = fs.MkdirAll("vendor/github.com", os.ModePerm)
@@ -173,9 +185,10 @@ func (s *MatcherSuite) SetUpTest(c *C) {
 func (s *MatcherSuite) TestDir_ReadPatterns(c *C) {
 	ps, err := ReadPatterns(s.GFS, nil)
 	c.Assert(err, IsNil)
-	c.Assert(ps, HasLen, 3)
+	c.Assert(ps, HasLen, 4)
 
 	m := NewMatcher(ps)
+	c.Assert(m.Match([]string{"exclude.crlf"}, true), Equals, true)
 	c.Assert(m.Match([]string{"ignore.crlf"}, true), Equals, true)
 	c.Assert(m.Match([]string{"vendor", "gopkg.in"}, true), Equals, true)
 	c.Assert(m.Match([]string{"vendor", "github.com"}, true), Equals, false)
diff --git a/plumbing/format/idxfile/decoder.go b/plumbing/format/idxfile/decoder.go
index 7768bd650..51a390489 100644
--- a/plumbing/format/idxfile/decoder.go
+++ b/plumbing/format/idxfile/decoder.go
@@ -12,9 +12,9 @@ import (
 var (
 	// ErrUnsupportedVersion is returned by Decode when the idx file version
 	// is not supported.
-	ErrUnsupportedVersion = errors.New("Unsupported version")
+	ErrUnsupportedVersion = errors.New("unsupported version")
 	// ErrMalformedIdxFile is returned by Decode when the idx file is corrupted.
-	ErrMalformedIdxFile = errors.New("Malformed IDX file")
+	ErrMalformedIdxFile = errors.New("malformed IDX file")
 )
 
 const (
diff --git a/plumbing/format/idxfile/encoder.go b/plumbing/format/idxfile/encoder.go
index 26b2e4d6b..6ac445ff6 100644
--- a/plumbing/format/idxfile/encoder.go
+++ b/plumbing/format/idxfile/encoder.go
@@ -1,10 +1,10 @@
 package idxfile
 
 import (
-	"crypto/sha1"
-	"hash"
+	"crypto"
 	"io"
 
+	"github.com/go-git/go-git/v5/plumbing/hash"
 	"github.com/go-git/go-git/v5/utils/binary"
 )
 
@@ -16,7 +16,7 @@ type Encoder struct {
 
 // NewEncoder returns a new stream encoder that writes to w.
 func NewEncoder(w io.Writer) *Encoder {
-	h := sha1.New()
+	h := hash.New(crypto.SHA1)
 	mw := io.MultiWriter(w, h)
 	return &Encoder{mw, h}
 }
diff --git a/plumbing/format/index/decoder.go b/plumbing/format/index/decoder.go
index 036b6365e..c4da20c08 100644
--- a/plumbing/format/index/decoder.go
+++ b/plumbing/format/index/decoder.go
@@ -3,15 +3,15 @@ package index
 import (
 	"bufio"
 	"bytes"
-	"crypto/sha1"
+	"crypto"
 	"errors"
-	"hash"
 	"io"
 	"io/ioutil"
 	"strconv"
 	"time"
 
 	"github.com/go-git/go-git/v5/plumbing"
+	"github.com/go-git/go-git/v5/plumbing/hash"
 	"github.com/go-git/go-git/v5/utils/binary"
 )
 
@@ -49,7 +49,7 @@ type Decoder struct {
 
 // NewDecoder returns a new decoder that reads from r.
 func NewDecoder(r io.Reader) *Decoder {
-	h := sha1.New()
+	h := hash.New(crypto.SHA1)
 	return &Decoder{
 		r:         io.TeeReader(r, h),
 		hash:      h,
diff --git a/plumbing/format/index/encoder.go b/plumbing/format/index/encoder.go
index 00d4e7a31..a91537870 100644
--- a/plumbing/format/index/encoder.go
+++ b/plumbing/format/index/encoder.go
@@ -2,19 +2,19 @@ package index
 
 import (
 	"bytes"
-	"crypto/sha1"
+	"crypto"
 	"errors"
-	"hash"
 	"io"
 	"sort"
 	"time"
 
+	"github.com/go-git/go-git/v5/plumbing/hash"
 	"github.com/go-git/go-git/v5/utils/binary"
 )
 
 var (
 	// EncodeVersionSupported is the range of supported index versions
-	EncodeVersionSupported uint32 = 2
+	EncodeVersionSupported uint32 = 3
 
 	// ErrInvalidTimestamp is returned by Encode if a Index with a Entry with
 	// negative timestamp values
@@ -29,16 +29,16 @@ type Encoder struct {
 
 // NewEncoder returns a new encoder that writes to w.
 func NewEncoder(w io.Writer) *Encoder {
-	h := sha1.New()
+	h := hash.New(crypto.SHA1)
 	mw := io.MultiWriter(w, h)
 	return &Encoder{mw, h}
 }
 
 // Encode writes the Index to the stream of the encoder.
 func (e *Encoder) Encode(idx *Index) error {
-	// TODO: support versions v3 and v4
+	// TODO: support v4
 	// TODO: support extensions
-	if idx.Version != EncodeVersionSupported {
+	if idx.Version > EncodeVersionSupported {
 		return ErrUnsupportedVersion
 	}
 
@@ -68,8 +68,12 @@ func (e *Encoder) encodeEntries(idx *Index) error {
 		if err := e.encodeEntry(entry); err != nil {
 			return err
 		}
+		entryLength := entryHeaderLength
+		if entry.IntentToAdd || entry.SkipWorktree {
+			entryLength += 2
+		}
 
-		wrote := entryHeaderLength + len(entry.Name)
+		wrote := entryLength + len(entry.Name)
 		if err := e.padEntry(wrote); err != nil {
 			return err
 		}
@@ -79,10 +83,6 @@ func (e *Encoder) encodeEntries(idx *Index) error {
 }
 
 func (e *Encoder) encodeEntry(entry *Entry) error {
-	if entry.IntentToAdd || entry.SkipWorktree {
-		return ErrUnsupportedVersion
-	}
-
 	sec, nsec, err := e.timeToUint32(&entry.CreatedAt)
 	if err != nil {
 		return err
@@ -110,9 +110,25 @@ func (e *Encoder) encodeEntry(entry *Entry) error {
 		entry.GID,
 		entry.Size,
 		entry.Hash[:],
-		flags,
 	}
 
+	flagsFlow := []interface{}{flags}
+
+	if entry.IntentToAdd || entry.SkipWorktree {
+		var extendedFlags uint16
+
+		if entry.IntentToAdd {
+			extendedFlags |= intentToAddMask
+		}
+		if entry.SkipWorktree {
+			extendedFlags |= skipWorkTreeMask
+		}
+
+		flagsFlow = []interface{}{flags | entryExtended, extendedFlags}
+	}
+
+	flow = append(flow, flagsFlow...)
+
 	if err := binary.Write(e.w, flow...); err != nil {
 		return err
 	}
diff --git a/plumbing/format/index/encoder_test.go b/plumbing/format/index/encoder_test.go
index b7a73cb14..25c24f14f 100644
--- a/plumbing/format/index/encoder_test.go
+++ b/plumbing/format/index/encoder_test.go
@@ -57,7 +57,7 @@ func (s *IndexSuite) TestEncode(c *C) {
 }
 
 func (s *IndexSuite) TestEncodeUnsupportedVersion(c *C) {
-	idx := &Index{Version: 3}
+	idx := &Index{Version: 4}
 
 	buf := bytes.NewBuffer(nil)
 	e := NewEncoder(buf)
@@ -67,24 +67,40 @@ func (s *IndexSuite) TestEncodeUnsupportedVersion(c *C) {
 
 func (s *IndexSuite) TestEncodeWithIntentToAddUnsupportedVersion(c *C) {
 	idx := &Index{
-		Version: 2,
+		Version: 3,
 		Entries: []*Entry{{IntentToAdd: true}},
 	}
 
 	buf := bytes.NewBuffer(nil)
 	e := NewEncoder(buf)
 	err := e.Encode(idx)
-	c.Assert(err, Equals, ErrUnsupportedVersion)
+	c.Assert(err, IsNil)
+
+	output := &Index{}
+	d := NewDecoder(buf)
+	err = d.Decode(output)
+	c.Assert(err, IsNil)
+
+	c.Assert(cmp.Equal(idx, output), Equals, true)
+	c.Assert(output.Entries[0].IntentToAdd, Equals, true)
 }
 
 func (s *IndexSuite) TestEncodeWithSkipWorktreeUnsupportedVersion(c *C) {
 	idx := &Index{
-		Version: 2,
+		Version: 3,
 		Entries: []*Entry{{SkipWorktree: true}},
 	}
 
 	buf := bytes.NewBuffer(nil)
 	e := NewEncoder(buf)
 	err := e.Encode(idx)
-	c.Assert(err, Equals, ErrUnsupportedVersion)
+	c.Assert(err, IsNil)
+
+	output := &Index{}
+	d := NewDecoder(buf)
+	err = d.Decode(output)
+	c.Assert(err, IsNil)
+
+	c.Assert(cmp.Equal(idx, output), Equals, true)
+	c.Assert(output.Entries[0].SkipWorktree, Equals, true)
 }
diff --git a/plumbing/format/index/index.go b/plumbing/format/index/index.go
index 649416a2b..f4c7647d3 100644
--- a/plumbing/format/index/index.go
+++ b/plumbing/format/index/index.go
@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"path/filepath"
+	"strings"
 	"time"
 
 	"github.com/go-git/go-git/v5/plumbing"
@@ -211,3 +212,20 @@ type EndOfIndexEntry struct {
 	//	their contents).
 	Hash plumbing.Hash
 }
+
+// SkipUnless applies patterns in the form of A, A/B, A/B/C
+// to the index to prevent the files from being checked out
+func (i *Index) SkipUnless(patterns []string) {
+	for _, e := range i.Entries {
+		var include bool
+		for _, pattern := range patterns {
+			if strings.HasPrefix(e.Name, pattern) {
+				include = true
+				break
+			}
+		}
+		if !include {
+			e.SkipWorktree = true
+		}
+	}
+}
diff --git a/plumbing/format/objfile/reader.go b/plumbing/format/objfile/reader.go
index b6b2ca06d..d7932f4ea 100644
--- a/plumbing/format/objfile/reader.go
+++ b/plumbing/format/objfile/reader.go
@@ -1,13 +1,13 @@
 package objfile
 
 import (
-	"compress/zlib"
 	"errors"
 	"io"
 	"strconv"
 
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/plumbing/format/packfile"
+	"github.com/go-git/go-git/v5/utils/sync"
 )
 
 var (
@@ -20,20 +20,22 @@ var (
 // Reader implements io.ReadCloser. Close should be called when finished with
 // the Reader. Close will not close the underlying io.Reader.
 type Reader struct {
-	multi  io.Reader
-	zlib   io.ReadCloser
-	hasher plumbing.Hasher
+	multi   io.Reader
+	zlib    io.Reader
+	zlibref sync.ZLibReader
+	hasher  plumbing.Hasher
 }
 
 // NewReader returns a new Reader reading from r.
 func NewReader(r io.Reader) (*Reader, error) {
-	zlib, err := zlib.NewReader(r)
+	zlib, err := sync.GetZlibReader(r)
 	if err != nil {
 		return nil, packfile.ErrZLib.AddDetails(err.Error())
 	}
 
 	return &Reader{
-		zlib: zlib,
+		zlib:    zlib.Reader,
+		zlibref: zlib,
 	}, nil
 }
 
@@ -110,5 +112,6 @@ func (r *Reader) Hash() plumbing.Hash {
 // Close releases any resources consumed by the Reader. Calling Close does not
 // close the wrapped io.Reader originally passed to NewReader.
 func (r *Reader) Close() error {
-	return r.zlib.Close()
+	sync.PutZlibReader(r.zlibref)
+	return nil
 }
diff --git a/plumbing/format/objfile/writer.go b/plumbing/format/objfile/writer.go
index 2a96a4370..0d0f15492 100644
--- a/plumbing/format/objfile/writer.go
+++ b/plumbing/format/objfile/writer.go
@@ -7,6 +7,7 @@ import (
 	"strconv"
 
 	"github.com/go-git/go-git/v5/plumbing"
+	"github.com/go-git/go-git/v5/utils/sync"
 )
 
 var (
@@ -18,9 +19,9 @@ var (
 // not close the underlying io.Writer.
 type Writer struct {
 	raw    io.Writer
-	zlib   io.WriteCloser
 	hasher plumbing.Hasher
 	multi  io.Writer
+	zlib   *zlib.Writer
 
 	closed  bool
 	pending int64 // number of unwritten bytes
@@ -31,9 +32,10 @@ type Writer struct {
 // The returned Writer implements io.WriteCloser. Close should be called when
 // finished with the Writer. Close will not close the underlying io.Writer.
 func NewWriter(w io.Writer) *Writer {
+	zlib := sync.GetZlibWriter(w)
 	return &Writer{
 		raw:  w,
-		zlib: zlib.NewWriter(w),
+		zlib: zlib,
 	}
 }
 
@@ -100,6 +102,7 @@ func (w *Writer) Hash() plumbing.Hash {
 // Calling Close does not close the wrapped io.Writer originally passed to
 // NewWriter.
 func (w *Writer) Close() error {
+	defer sync.PutZlibWriter(w.zlib)
 	if err := w.zlib.Close(); err != nil {
 		return err
 	}
diff --git a/plumbing/format/packfile/common.go b/plumbing/format/packfile/common.go
index df423ad50..36c5ef5b8 100644
--- a/plumbing/format/packfile/common.go
+++ b/plumbing/format/packfile/common.go
@@ -1,10 +1,7 @@
 package packfile
 
 import (
-	"bytes"
-	"compress/zlib"
 	"io"
-	"sync"
 
 	"github.com/go-git/go-git/v5/plumbing/storer"
 	"github.com/go-git/go-git/v5/utils/ioutil"
@@ -61,18 +58,3 @@ func WritePackfileToObjectStorage(
 
 	return err
 }
-
-var bufPool = sync.Pool{
-	New: func() interface{} {
-		return bytes.NewBuffer(nil)
-	},
-}
-
-var zlibInitBytes = []byte{0x78, 0x9c, 0x01, 0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0x01}
-
-var zlibReaderPool = sync.Pool{
-	New: func() interface{} {
-		r, _ := zlib.NewReader(bytes.NewReader(zlibInitBytes))
-		return r
-	},
-}
diff --git a/plumbing/format/packfile/delta_test.go b/plumbing/format/packfile/delta_test.go
index 98f53f6d6..137e4859b 100644
--- a/plumbing/format/packfile/delta_test.go
+++ b/plumbing/format/packfile/delta_test.go
@@ -1,8 +1,11 @@
 package packfile
 
 import (
+	"bytes"
+	"io/ioutil"
 	"math/rand"
 
+	"github.com/go-git/go-git/v5/plumbing"
 	. "gopkg.in/check.v1"
 )
 
@@ -97,6 +100,32 @@ func (s *DeltaSuite) TestAddDelta(c *C) {
 	}
 }
 
+func (s *DeltaSuite) TestAddDeltaReader(c *C) {
+	for _, t := range s.testCases {
+		baseBuf := genBytes(t.base)
+		baseObj := &plumbing.MemoryObject{}
+		baseObj.Write(baseBuf)
+
+		targetBuf := genBytes(t.target)
+
+		delta := DiffDelta(baseBuf, targetBuf)
+		deltaRC := ioutil.NopCloser(bytes.NewReader(delta))
+
+		c.Log("Executing test case:", t.description)
+
+		resultRC, err := ReaderFromDelta(baseObj, deltaRC)
+		c.Assert(err, IsNil)
+
+		result, err := ioutil.ReadAll(resultRC)
+		c.Assert(err, IsNil)
+
+		err = resultRC.Close()
+		c.Assert(err, IsNil)
+
+		c.Assert(result, DeepEquals, targetBuf)
+	}
+}
+
 func (s *DeltaSuite) TestIncompleteDelta(c *C) {
 	for _, t := range s.testCases {
 		c.Log("Incomplete delta on:", t.description)
@@ -125,3 +154,25 @@ func (s *DeltaSuite) TestMaxCopySizeDelta(c *C) {
 	c.Assert(err, IsNil)
 	c.Assert(result, DeepEquals, targetBuf)
 }
+
+func (s *DeltaSuite) TestMaxCopySizeDeltaReader(c *C) {
+	baseBuf := randBytes(maxCopySize)
+	baseObj := &plumbing.MemoryObject{}
+	baseObj.Write(baseBuf)
+
+	targetBuf := baseBuf[0:]
+	targetBuf = append(targetBuf, byte(1))
+
+	delta := DiffDelta(baseBuf, targetBuf)
+	deltaRC := ioutil.NopCloser(bytes.NewReader(delta))
+
+	resultRC, err := ReaderFromDelta(baseObj, deltaRC)
+	c.Assert(err, IsNil)
+
+	result, err := ioutil.ReadAll(resultRC)
+	c.Assert(err, IsNil)
+
+	err = resultRC.Close()
+	c.Assert(err, IsNil)
+	c.Assert(result, DeepEquals, targetBuf)
+}
diff --git a/plumbing/format/packfile/diff_delta.go b/plumbing/format/packfile/diff_delta.go
index 1951b34ef..2c7a33581 100644
--- a/plumbing/format/packfile/diff_delta.go
+++ b/plumbing/format/packfile/diff_delta.go
@@ -5,6 +5,7 @@ import (
 
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/utils/ioutil"
+	"github.com/go-git/go-git/v5/utils/sync"
 )
 
 // See https://github.com/jelmer/dulwich/blob/master/dulwich/pack.py and
@@ -43,18 +44,16 @@ func getDelta(index *deltaIndex, base, target plumbing.EncodedObject) (o plumbin
 
 	defer ioutil.CheckClose(tr, &err)
 
-	bb := bufPool.Get().(*bytes.Buffer)
-	defer bufPool.Put(bb)
-	bb.Reset()
+	bb := sync.GetBytesBuffer()
+	defer sync.PutBytesBuffer(bb)
 
 	_, err = bb.ReadFrom(br)
 	if err != nil {
 		return nil, err
 	}
 
-	tb := bufPool.Get().(*bytes.Buffer)
-	defer bufPool.Put(tb)
-	tb.Reset()
+	tb := sync.GetBytesBuffer()
+	defer sync.PutBytesBuffer(tb)
 
 	_, err = tb.ReadFrom(tr)
 	if err != nil {
@@ -80,9 +79,8 @@ func DiffDelta(src, tgt []byte) []byte {
 }
 
 func diffDelta(index *deltaIndex, src []byte, tgt []byte) []byte {
-	buf := bufPool.Get().(*bytes.Buffer)
-	defer bufPool.Put(buf)
-	buf.Reset()
+	buf := sync.GetBytesBuffer()
+	defer sync.PutBytesBuffer(buf)
 	buf.Write(deltaEncodeSize(len(src)))
 	buf.Write(deltaEncodeSize(len(tgt)))
 
@@ -90,9 +88,8 @@ func diffDelta(index *deltaIndex, src []byte, tgt []byte) []byte {
 		index.init(src)
 	}
 
-	ibuf := bufPool.Get().(*bytes.Buffer)
-	defer bufPool.Put(ibuf)
-	ibuf.Reset()
+	ibuf := sync.GetBytesBuffer()
+	defer sync.PutBytesBuffer(ibuf)
 	for i := 0; i < len(tgt); i++ {
 		offset, l := index.findMatch(src, tgt, i)
 
diff --git a/plumbing/format/packfile/encoder.go b/plumbing/format/packfile/encoder.go
index 5501f8861..a8a7e967b 100644
--- a/plumbing/format/packfile/encoder.go
+++ b/plumbing/format/packfile/encoder.go
@@ -2,11 +2,12 @@ package packfile
 
 import (
 	"compress/zlib"
-	"crypto/sha1"
+	"crypto"
 	"fmt"
 	"io"
 
 	"github.com/go-git/go-git/v5/plumbing"
+	"github.com/go-git/go-git/v5/plumbing/hash"
 	"github.com/go-git/go-git/v5/plumbing/storer"
 	"github.com/go-git/go-git/v5/utils/binary"
 	"github.com/go-git/go-git/v5/utils/ioutil"
@@ -28,7 +29,7 @@ type Encoder struct {
 // OFSDeltaObject. To use Reference deltas, set useRefDeltas to true.
 func NewEncoder(w io.Writer, s storer.EncodedObjectStorer, useRefDeltas bool) *Encoder {
 	h := plumbing.Hasher{
-		Hash: sha1.New(),
+		Hash: hash.New(crypto.SHA1),
 	}
 	mw := io.MultiWriter(w, h)
 	ow := newOffsetWriter(mw)
diff --git a/plumbing/format/packfile/encoder_advanced_test.go b/plumbing/format/packfile/encoder_advanced_test.go
index 95db5c082..15c0fba40 100644
--- a/plumbing/format/packfile/encoder_advanced_test.go
+++ b/plumbing/format/packfile/encoder_advanced_test.go
@@ -105,7 +105,7 @@ func (s *EncoderAdvancedSuite) testEncodeDecode(
 	_, err = f.Seek(0, io.SeekStart)
 	c.Assert(err, IsNil)
 
-	p := NewPackfile(index, fs, f)
+	p := NewPackfile(index, fs, f, 0)
 
 	decodeHash, err := p.ID()
 	c.Assert(err, IsNil)
diff --git a/plumbing/format/packfile/encoder_test.go b/plumbing/format/packfile/encoder_test.go
index d2db892a6..c9d49c3b5 100644
--- a/plumbing/format/packfile/encoder_test.go
+++ b/plumbing/format/packfile/encoder_test.go
@@ -318,7 +318,7 @@ func packfileFromReader(c *C, buf *bytes.Buffer) (*Packfile, func()) {
 	index, err := w.Index()
 	c.Assert(err, IsNil)
 
-	return NewPackfile(index, fs, file), func() {
+	return NewPackfile(index, fs, file, 0), func() {
 		c.Assert(file.Close(), IsNil)
 	}
 }
diff --git a/plumbing/format/packfile/fsobject.go b/plumbing/format/packfile/fsobject.go
index c5edaf52e..238339daf 100644
--- a/plumbing/format/packfile/fsobject.go
+++ b/plumbing/format/packfile/fsobject.go
@@ -7,19 +7,20 @@ import (
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/plumbing/cache"
 	"github.com/go-git/go-git/v5/plumbing/format/idxfile"
+	"github.com/go-git/go-git/v5/utils/ioutil"
 )
 
 // FSObject is an object from the packfile on the filesystem.
 type FSObject struct {
-	hash   plumbing.Hash
-	h      *ObjectHeader
-	offset int64
-	size   int64
-	typ    plumbing.ObjectType
-	index  idxfile.Index
-	fs     billy.Filesystem
-	path   string
-	cache  cache.Object
+	hash                 plumbing.Hash
+	offset               int64
+	size                 int64
+	typ                  plumbing.ObjectType
+	index                idxfile.Index
+	fs                   billy.Filesystem
+	path                 string
+	cache                cache.Object
+	largeObjectThreshold int64
 }
 
 // NewFSObject creates a new filesystem object.
@@ -32,16 +33,18 @@ func NewFSObject(
 	fs billy.Filesystem,
 	path string,
 	cache cache.Object,
+	largeObjectThreshold int64,
 ) *FSObject {
 	return &FSObject{
-		hash:   hash,
-		offset: offset,
-		size:   contentSize,
-		typ:    finalType,
-		index:  index,
-		fs:     fs,
-		path:   path,
-		cache:  cache,
+		hash:                 hash,
+		offset:               offset,
+		size:                 contentSize,
+		typ:                  finalType,
+		index:                index,
+		fs:                   fs,
+		path:                 path,
+		cache:                cache,
+		largeObjectThreshold: largeObjectThreshold,
 	}
 }
 
@@ -62,7 +65,21 @@ func (o *FSObject) Reader() (io.ReadCloser, error) {
 		return nil, err
 	}
 
-	p := NewPackfileWithCache(o.index, nil, f, o.cache)
+	p := NewPackfileWithCache(o.index, nil, f, o.cache, o.largeObjectThreshold)
+	if o.largeObjectThreshold > 0 && o.size > o.largeObjectThreshold {
+		// We have a big object
+		h, err := p.objectHeaderAtOffset(o.offset)
+		if err != nil {
+			return nil, err
+		}
+
+		r, err := p.getReaderDirect(h)
+		if err != nil {
+			_ = f.Close()
+			return nil, err
+		}
+		return ioutil.NewReadCloserWithCloser(r, f.Close), nil
+	}
 	r, err := p.getObjectContent(o.offset)
 	if err != nil {
 		_ = f.Close()
@@ -100,17 +117,3 @@ func (o *FSObject) Type() plumbing.ObjectType {
 func (o *FSObject) Writer() (io.WriteCloser, error) {
 	return nil, nil
 }
-
-type objectReader struct {
-	io.ReadCloser
-	f billy.File
-}
-
-func (r *objectReader) Close() error {
-	if err := r.ReadCloser.Close(); err != nil {
-		_ = r.f.Close()
-		return err
-	}
-
-	return r.f.Close()
-}
diff --git a/plumbing/format/packfile/packfile.go b/plumbing/format/packfile/packfile.go
index ddd7f62fc..685270225 100644
--- a/plumbing/format/packfile/packfile.go
+++ b/plumbing/format/packfile/packfile.go
@@ -2,6 +2,7 @@ package packfile
 
 import (
 	"bytes"
+	"fmt"
 	"io"
 	"os"
 
@@ -11,6 +12,7 @@ import (
 	"github.com/go-git/go-git/v5/plumbing/format/idxfile"
 	"github.com/go-git/go-git/v5/plumbing/storer"
 	"github.com/go-git/go-git/v5/utils/ioutil"
+	"github.com/go-git/go-git/v5/utils/sync"
 )
 
 var (
@@ -35,11 +37,12 @@ const smallObjectThreshold = 16 * 1024
 // Packfile allows retrieving information from inside a packfile.
 type Packfile struct {
 	idxfile.Index
-	fs             billy.Filesystem
-	file           billy.File
-	s              *Scanner
-	deltaBaseCache cache.Object
-	offsetToType   map[int64]plumbing.ObjectType
+	fs                   billy.Filesystem
+	file                 billy.File
+	s                    *Scanner
+	deltaBaseCache       cache.Object
+	offsetToType         map[int64]plumbing.ObjectType
+	largeObjectThreshold int64
 }
 
 // NewPackfileWithCache creates a new Packfile with the given object cache.
@@ -50,6 +53,7 @@ func NewPackfileWithCache(
 	fs billy.Filesystem,
 	file billy.File,
 	cache cache.Object,
+	largeObjectThreshold int64,
 ) *Packfile {
 	s := NewScanner(file)
 	return &Packfile{
@@ -59,6 +63,7 @@ func NewPackfileWithCache(
 		s,
 		cache,
 		make(map[int64]plumbing.ObjectType),
+		largeObjectThreshold,
 	}
 }
 
@@ -66,8 +71,8 @@ func NewPackfileWithCache(
 // and packfile idx.
 // If the filesystem is provided, the packfile will return FSObjects, otherwise
 // it will return MemoryObjects.
-func NewPackfile(index idxfile.Index, fs billy.Filesystem, file billy.File) *Packfile {
-	return NewPackfileWithCache(index, fs, file, cache.NewObjectLRUDefault())
+func NewPackfile(index idxfile.Index, fs billy.Filesystem, file billy.File, largeObjectThreshold int64) *Packfile {
+	return NewPackfileWithCache(index, fs, file, cache.NewObjectLRUDefault(), largeObjectThreshold)
 }
 
 // Get retrieves the encoded object in the packfile with the given hash.
@@ -133,9 +138,8 @@ func (p *Packfile) getObjectSize(h *ObjectHeader) (int64, error) {
 	case plumbing.CommitObject, plumbing.TreeObject, plumbing.BlobObject, plumbing.TagObject:
 		return h.Length, nil
 	case plumbing.REFDeltaObject, plumbing.OFSDeltaObject:
-		buf := bufPool.Get().(*bytes.Buffer)
-		defer bufPool.Put(buf)
-		buf.Reset()
+		buf := sync.GetBytesBuffer()
+		defer sync.PutBytesBuffer(buf)
 
 		if _, _, err := p.s.NextObject(buf); err != nil {
 			return 0, err
@@ -222,9 +226,9 @@ func (p *Packfile) getNextObject(h *ObjectHeader, hash plumbing.Hash) (plumbing.
 		// For delta objects we read the delta data and apply the small object
 		// optimization only if the expanded version of the object still meets
 		// the small object threshold condition.
-		buf := bufPool.Get().(*bytes.Buffer)
-		defer bufPool.Put(buf)
-		buf.Reset()
+		buf := sync.GetBytesBuffer()
+		defer sync.PutBytesBuffer(buf)
+
 		if _, _, err := p.s.NextObject(buf); err != nil {
 			return nil, err
 		}
@@ -263,6 +267,7 @@ func (p *Packfile) getNextObject(h *ObjectHeader, hash plumbing.Hash) (plumbing.
 		p.fs,
 		p.file.Name(),
 		p.deltaBaseCache,
+		p.largeObjectThreshold,
 	), nil
 }
 
@@ -282,6 +287,49 @@ func (p *Packfile) getObjectContent(offset int64) (io.ReadCloser, error) {
 	return obj.Reader()
 }
 
+func asyncReader(p *Packfile) (io.ReadCloser, error) {
+	reader := ioutil.NewReaderUsingReaderAt(p.file, p.s.r.offset)
+	zr, err := sync.GetZlibReader(reader)
+	if err != nil {
+		return nil, fmt.Errorf("zlib reset error: %s", err)
+	}
+
+	return ioutil.NewReadCloserWithCloser(zr.Reader, func() error {
+		sync.PutZlibReader(zr)
+		return nil
+	}), nil
+
+}
+
+func (p *Packfile) getReaderDirect(h *ObjectHeader) (io.ReadCloser, error) {
+	switch h.Type {
+	case plumbing.CommitObject, plumbing.TreeObject, plumbing.BlobObject, plumbing.TagObject:
+		return asyncReader(p)
+	case plumbing.REFDeltaObject:
+		deltaRc, err := asyncReader(p)
+		if err != nil {
+			return nil, err
+		}
+		r, err := p.readREFDeltaObjectContent(h, deltaRc)
+		if err != nil {
+			return nil, err
+		}
+		return r, nil
+	case plumbing.OFSDeltaObject:
+		deltaRc, err := asyncReader(p)
+		if err != nil {
+			return nil, err
+		}
+		r, err := p.readOFSDeltaObjectContent(h, deltaRc)
+		if err != nil {
+			return nil, err
+		}
+		return r, nil
+	default:
+		return nil, ErrInvalidObject.AddDetails("type %q", h.Type)
+	}
+}
+
 func (p *Packfile) getNextMemoryObject(h *ObjectHeader) (plumbing.EncodedObject, error) {
 	var obj = new(plumbing.MemoryObject)
 	obj.SetSize(h.Length)
@@ -323,9 +371,9 @@ func (p *Packfile) fillRegularObjectContent(obj plumbing.EncodedObject) (err err
 }
 
 func (p *Packfile) fillREFDeltaObjectContent(obj plumbing.EncodedObject, ref plumbing.Hash) error {
-	buf := bufPool.Get().(*bytes.Buffer)
-	defer bufPool.Put(buf)
-	buf.Reset()
+	buf := sync.GetBytesBuffer()
+	defer sync.PutBytesBuffer(buf)
+
 	_, _, err := p.s.NextObject(buf)
 	if err != nil {
 		return err
@@ -334,6 +382,20 @@ func (p *Packfile) fillREFDeltaObjectContent(obj plumbing.EncodedObject, ref plu
 	return p.fillREFDeltaObjectContentWithBuffer(obj, ref, buf)
 }
 
+func (p *Packfile) readREFDeltaObjectContent(h *ObjectHeader, deltaRC io.Reader) (io.ReadCloser, error) {
+	var err error
+
+	base, ok := p.cacheGet(h.Reference)
+	if !ok {
+		base, err = p.Get(h.Reference)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return ReaderFromDelta(base, deltaRC)
+}
+
 func (p *Packfile) fillREFDeltaObjectContentWithBuffer(obj plumbing.EncodedObject, ref plumbing.Hash, buf *bytes.Buffer) error {
 	var err error
 
@@ -353,9 +415,9 @@ func (p *Packfile) fillREFDeltaObjectContentWithBuffer(obj plumbing.EncodedObjec
 }
 
 func (p *Packfile) fillOFSDeltaObjectContent(obj plumbing.EncodedObject, offset int64) error {
-	buf := bufPool.Get().(*bytes.Buffer)
-	defer bufPool.Put(buf)
-	buf.Reset()
+	buf := sync.GetBytesBuffer()
+	defer sync.PutBytesBuffer(buf)
+
 	_, _, err := p.s.NextObject(buf)
 	if err != nil {
 		return err
@@ -364,6 +426,20 @@ func (p *Packfile) fillOFSDeltaObjectContent(obj plumbing.EncodedObject, offset
 	return p.fillOFSDeltaObjectContentWithBuffer(obj, offset, buf)
 }
 
+func (p *Packfile) readOFSDeltaObjectContent(h *ObjectHeader, deltaRC io.Reader) (io.ReadCloser, error) {
+	hash, err := p.FindHash(h.OffsetReference)
+	if err != nil {
+		return nil, err
+	}
+
+	base, err := p.objectAtOffset(h.OffsetReference, hash)
+	if err != nil {
+		return nil, err
+	}
+
+	return ReaderFromDelta(base, deltaRC)
+}
+
 func (p *Packfile) fillOFSDeltaObjectContentWithBuffer(obj plumbing.EncodedObject, offset int64, buf *bytes.Buffer) error {
 	hash, err := p.FindHash(offset)
 	if err != nil {
diff --git a/plumbing/format/packfile/packfile_test.go b/plumbing/format/packfile/packfile_test.go
index 60c7c7341..2eb099df6 100644
--- a/plumbing/format/packfile/packfile_test.go
+++ b/plumbing/format/packfile/packfile_test.go
@@ -8,7 +8,6 @@ import (
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/plumbing/format/idxfile"
 	"github.com/go-git/go-git/v5/plumbing/format/packfile"
-	"github.com/go-git/go-git/v5/plumbing/storer"
 	. "gopkg.in/check.v1"
 )
 
@@ -111,7 +110,7 @@ func (s *PackfileSuite) SetUpTest(c *C) {
 	s.idx = idxfile.NewMemoryIndex()
 	c.Assert(idxfile.NewDecoder(s.f.Idx()).Decode(s.idx), IsNil)
 
-	s.p = packfile.NewPackfile(s.idx, fixtures.Filesystem, s.f.Packfile())
+	s.p = packfile.NewPackfile(s.idx, fixtures.Filesystem, s.f.Packfile(), 0)
 }
 
 func (s *PackfileSuite) TearDownTest(c *C) {
@@ -122,7 +121,7 @@ func (s *PackfileSuite) TestDecode(c *C) {
 	fixtures.Basic().ByTag("packfile").Test(c, func(f *fixtures.Fixture) {
 		index := getIndexFromIdxFile(f.Idx())
 
-		p := packfile.NewPackfile(index, fixtures.Filesystem, f.Packfile())
+		p := packfile.NewPackfile(index, fixtures.Filesystem, f.Packfile(), 0)
 		defer p.Close()
 
 		for _, h := range expectedHashes {
@@ -138,7 +137,7 @@ func (s *PackfileSuite) TestDecodeByTypeRefDelta(c *C) {
 
 	index := getIndexFromIdxFile(f.Idx())
 
-	packfile := packfile.NewPackfile(index, fixtures.Filesystem, f.Packfile())
+	packfile := packfile.NewPackfile(index, fixtures.Filesystem, f.Packfile(), 0)
 	defer packfile.Close()
 
 	iter, err := packfile.GetByType(plumbing.CommitObject)
@@ -171,7 +170,7 @@ func (s *PackfileSuite) TestDecodeByType(c *C) {
 		for _, t := range ts {
 			index := getIndexFromIdxFile(f.Idx())
 
-			packfile := packfile.NewPackfile(index, fixtures.Filesystem, f.Packfile())
+			packfile := packfile.NewPackfile(index, fixtures.Filesystem, f.Packfile(), 0)
 			defer packfile.Close()
 
 			iter, err := packfile.GetByType(t)
@@ -189,7 +188,7 @@ func (s *PackfileSuite) TestDecodeByTypeConstructor(c *C) {
 	f := fixtures.Basic().ByTag("packfile").One()
 	index := getIndexFromIdxFile(f.Idx())
 
-	packfile := packfile.NewPackfile(index, fixtures.Filesystem, f.Packfile())
+	packfile := packfile.NewPackfile(index, fixtures.Filesystem, f.Packfile(), 0)
 	defer packfile.Close()
 
 	_, err := packfile.GetByType(plumbing.OFSDeltaObject)
@@ -236,22 +235,6 @@ var expectedHashes = []string{
 	"7e59600739c96546163833214c36459e324bad0a",
 }
 
-func assertObjects(c *C, s storer.EncodedObjectStorer, expects []string) {
-	i, err := s.IterEncodedObjects(plumbing.AnyObject)
-	c.Assert(err, IsNil)
-
-	var count int
-	err = i.ForEach(func(plumbing.EncodedObject) error { count++; return nil })
-	c.Assert(err, IsNil)
-	c.Assert(count, Equals, len(expects))
-
-	for _, exp := range expects {
-		obt, err := s.EncodedObject(plumbing.AnyObject, plumbing.NewHash(exp))
-		c.Assert(err, IsNil)
-		c.Assert(obt.Hash().String(), Equals, exp)
-	}
-}
-
 func getIndexFromIdxFile(r io.Reader) idxfile.Index {
 	idx := idxfile.NewMemoryIndex()
 	if err := idxfile.NewDecoder(r).Decode(idx); err != nil {
@@ -266,7 +249,7 @@ func (s *PackfileSuite) TestSize(c *C) {
 
 	index := getIndexFromIdxFile(f.Idx())
 
-	packfile := packfile.NewPackfile(index, fixtures.Filesystem, f.Packfile())
+	packfile := packfile.NewPackfile(index, fixtures.Filesystem, f.Packfile(), 0)
 	defer packfile.Close()
 
 	// Get the size of binary.jpg, which is not delta-encoded.
diff --git a/plumbing/format/packfile/parser.go b/plumbing/format/packfile/parser.go
index 4b5a5708c..522c146f2 100644
--- a/plumbing/format/packfile/parser.go
+++ b/plumbing/format/packfile/parser.go
@@ -10,6 +10,7 @@ import (
 	"github.com/go-git/go-git/v5/plumbing/cache"
 	"github.com/go-git/go-git/v5/plumbing/storer"
 	"github.com/go-git/go-git/v5/utils/ioutil"
+	"github.com/go-git/go-git/v5/utils/sync"
 )
 
 var (
@@ -46,7 +47,6 @@ type Parser struct {
 	oi         []*objectInfo
 	oiByHash   map[plumbing.Hash]*objectInfo
 	oiByOffset map[int64]*objectInfo
-	hashOffset map[plumbing.Hash]int64
 	checksum   plumbing.Hash
 
 	cache *cache.BufferLRU
@@ -176,7 +176,8 @@ func (p *Parser) init() error {
 }
 
 func (p *Parser) indexObjects() error {
-	buf := new(bytes.Buffer)
+	buf := sync.GetBytesBuffer()
+	defer sync.PutBytesBuffer(buf)
 
 	for i := uint32(0); i < p.count; i++ {
 		buf.Reset()
@@ -220,6 +221,7 @@ func (p *Parser) indexObjects() error {
 			ota = newBaseObject(oh.Offset, oh.Length, t)
 		}
 
+		buf.Grow(int(oh.Length))
 		_, crc, err := p.scanner.NextObject(buf)
 		if err != nil {
 			return err
@@ -265,7 +267,9 @@ func (p *Parser) indexObjects() error {
 }
 
 func (p *Parser) resolveDeltas() error {
-	buf := &bytes.Buffer{}
+	buf := sync.GetBytesBuffer()
+	defer sync.PutBytesBuffer(buf)
+
 	for _, obj := range p.oi {
 		buf.Reset()
 		err := p.get(obj, buf)
@@ -287,6 +291,7 @@ func (p *Parser) resolveDeltas() error {
 				if err := p.resolveObject(stdioutil.Discard, child, content); err != nil {
 					return err
 				}
+				p.resolveExternalRef(child)
 			}
 
 			// Remove the delta from the cache.
@@ -299,6 +304,16 @@ func (p *Parser) resolveDeltas() error {
 	return nil
 }
 
+func (p *Parser) resolveExternalRef(o *objectInfo) {
+	if ref, ok := p.oiByHash[o.SHA1]; ok && ref.ExternalRef {
+		p.oiByHash[o.SHA1] = o
+		o.Children = ref.Children
+		for _, c := range o.Children {
+			c.Parent = o
+		}
+	}
+}
+
 func (p *Parser) get(o *objectInfo, buf *bytes.Buffer) (err error) {
 	if !o.ExternalRef { // skip cache check for placeholder parents
 		b, ok := p.cache.Get(o.Offset)
@@ -336,9 +351,8 @@ func (p *Parser) get(o *objectInfo, buf *bytes.Buffer) (err error) {
 	}
 
 	if o.DiskType.IsDelta() {
-		b := bufPool.Get().(*bytes.Buffer)
-		defer bufPool.Put(b)
-		b.Reset()
+		b := sync.GetBytesBuffer()
+		defer sync.PutBytesBuffer(b)
 		err := p.get(o.Parent, b)
 		if err != nil {
 			return err
@@ -372,9 +386,8 @@ func (p *Parser) resolveObject(
 	if !o.DiskType.IsDelta() {
 		return nil
 	}
-	buf := bufPool.Get().(*bytes.Buffer)
-	defer bufPool.Put(buf)
-	buf.Reset()
+	buf := sync.GetBytesBuffer()
+	defer sync.PutBytesBuffer(buf)
 	err := p.readData(buf, o)
 	if err != nil {
 		return err
diff --git a/plumbing/format/packfile/parser_test.go b/plumbing/format/packfile/parser_test.go
index b0b4af82a..651d05f3d 100644
--- a/plumbing/format/packfile/parser_test.go
+++ b/plumbing/format/packfile/parser_test.go
@@ -10,8 +10,10 @@ import (
 	fixtures "github.com/go-git/go-git-fixtures/v4"
 	"github.com/go-git/go-git/v5"
 	"github.com/go-git/go-git/v5/plumbing"
+	"github.com/go-git/go-git/v5/plumbing/cache"
 	"github.com/go-git/go-git/v5/plumbing/format/packfile"
 	"github.com/go-git/go-git/v5/plumbing/storer"
+	"github.com/go-git/go-git/v5/storage/filesystem"
 	. "gopkg.in/check.v1"
 )
 
@@ -132,6 +134,19 @@ func (s *ParserSuite) TestThinPack(c *C) {
 
 }
 
+func (s *ParserSuite) TestResolveExternalRefsInThinPack(c *C) {
+	extRefsThinPack := fixtures.ByTag("codecommit").One()
+
+	scanner := packfile.NewScanner(extRefsThinPack.Packfile())
+
+	obs := new(testObserver)
+	parser, err := packfile.NewParser(scanner, obs)
+	c.Assert(err, IsNil)
+
+	_, err = parser.Parse()
+	c.Assert(err, IsNil)
+}
+
 type observerObject struct {
 	hash   string
 	otype  plumbing.ObjectType
@@ -235,3 +250,29 @@ func BenchmarkParseBasic(b *testing.B) {
 		}
 	}
 }
+
+func BenchmarkParser(b *testing.B) {
+	f := fixtures.Basic().One()
+	defer fixtures.Clean()
+
+	b.ResetTimer()
+	for n := 0; n < b.N; n++ {
+		b.StopTimer()
+		scanner := packfile.NewScanner(f.Packfile())
+		fs := osfs.New(os.TempDir())
+		storage := filesystem.NewStorage(fs, cache.NewObjectLRUDefault())
+
+		parser, err := packfile.NewParserWithStorage(scanner, storage)
+		if err != nil {
+			b.Error(err)
+		}
+
+		b.StartTimer()
+		_, err = parser.Parse()
+
+		b.StopTimer()
+		if err != nil {
+			b.Error(err)
+		}
+	}
+}
diff --git a/plumbing/format/packfile/patch_delta.go b/plumbing/format/packfile/patch_delta.go
index 9e90f30a7..f00562d63 100644
--- a/plumbing/format/packfile/patch_delta.go
+++ b/plumbing/format/packfile/patch_delta.go
@@ -1,12 +1,15 @@
 package packfile
 
 import (
+	"bufio"
 	"bytes"
 	"errors"
 	"io"
+	"math"
 
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/utils/ioutil"
+	"github.com/go-git/go-git/v5/utils/sync"
 )
 
 // See https://github.com/git/git/blob/49fa3dc76179e04b0833542fa52d0f287a4955ac/delta.h
@@ -32,18 +35,16 @@ func ApplyDelta(target, base plumbing.EncodedObject, delta []byte) (err error) {
 
 	defer ioutil.CheckClose(w, &err)
 
-	buf := bufPool.Get().(*bytes.Buffer)
-	defer bufPool.Put(buf)
-	buf.Reset()
+	buf := sync.GetBytesBuffer()
+	defer sync.PutBytesBuffer(buf)
 	_, err = buf.ReadFrom(r)
 	if err != nil {
 		return err
 	}
 	src := buf.Bytes()
 
-	dst := bufPool.Get().(*bytes.Buffer)
-	defer bufPool.Put(dst)
-	dst.Reset()
+	dst := sync.GetBytesBuffer()
+	defer sync.PutBytesBuffer(dst)
 	err = patchDelta(dst, src, delta)
 	if err != nil {
 		return err
@@ -51,9 +52,9 @@ func ApplyDelta(target, base plumbing.EncodedObject, delta []byte) (err error) {
 
 	target.SetSize(int64(dst.Len()))
 
-	b := byteSlicePool.Get().([]byte)
-	_, err = io.CopyBuffer(w, dst, b)
-	byteSlicePool.Put(b)
+	b := sync.GetByteSlice()
+	_, err = io.CopyBuffer(w, dst, *b)
+	sync.PutByteSlice(b)
 	return err
 }
 
@@ -73,6 +74,131 @@ func PatchDelta(src, delta []byte) ([]byte, error) {
 	return b.Bytes(), nil
 }
 
+func ReaderFromDelta(base plumbing.EncodedObject, deltaRC io.Reader) (io.ReadCloser, error) {
+	deltaBuf := bufio.NewReaderSize(deltaRC, 1024)
+	srcSz, err := decodeLEB128ByteReader(deltaBuf)
+	if err != nil {
+		if err == io.EOF {
+			return nil, ErrInvalidDelta
+		}
+		return nil, err
+	}
+	if srcSz != uint(base.Size()) {
+		return nil, ErrInvalidDelta
+	}
+
+	targetSz, err := decodeLEB128ByteReader(deltaBuf)
+	if err != nil {
+		if err == io.EOF {
+			return nil, ErrInvalidDelta
+		}
+		return nil, err
+	}
+	remainingTargetSz := targetSz
+
+	dstRd, dstWr := io.Pipe()
+
+	go func() {
+		baseRd, err := base.Reader()
+		if err != nil {
+			_ = dstWr.CloseWithError(ErrInvalidDelta)
+			return
+		}
+		defer baseRd.Close()
+
+		baseBuf := bufio.NewReader(baseRd)
+		basePos := uint(0)
+
+		for {
+			cmd, err := deltaBuf.ReadByte()
+			if err == io.EOF {
+				_ = dstWr.CloseWithError(ErrInvalidDelta)
+				return
+			}
+			if err != nil {
+				_ = dstWr.CloseWithError(err)
+				return
+			}
+
+			if isCopyFromSrc(cmd) {
+				offset, err := decodeOffsetByteReader(cmd, deltaBuf)
+				if err != nil {
+					_ = dstWr.CloseWithError(err)
+					return
+				}
+				sz, err := decodeSizeByteReader(cmd, deltaBuf)
+				if err != nil {
+					_ = dstWr.CloseWithError(err)
+					return
+				}
+
+				if invalidSize(sz, targetSz) ||
+					invalidOffsetSize(offset, sz, srcSz) {
+					_ = dstWr.Close()
+					return
+				}
+
+				discard := offset - basePos
+				if basePos > offset {
+					_ = baseRd.Close()
+					baseRd, err = base.Reader()
+					if err != nil {
+						_ = dstWr.CloseWithError(ErrInvalidDelta)
+						return
+					}
+					baseBuf.Reset(baseRd)
+					discard = offset
+				}
+				for discard > math.MaxInt32 {
+					n, err := baseBuf.Discard(math.MaxInt32)
+					if err != nil {
+						_ = dstWr.CloseWithError(err)
+						return
+					}
+					basePos += uint(n)
+					discard -= uint(n)
+				}
+				for discard > 0 {
+					n, err := baseBuf.Discard(int(discard))
+					if err != nil {
+						_ = dstWr.CloseWithError(err)
+						return
+					}
+					basePos += uint(n)
+					discard -= uint(n)
+				}
+				if _, err := io.Copy(dstWr, io.LimitReader(baseBuf, int64(sz))); err != nil {
+					_ = dstWr.CloseWithError(err)
+					return
+				}
+				remainingTargetSz -= sz
+				basePos += sz
+			} else if isCopyFromDelta(cmd) {
+				sz := uint(cmd) // cmd is the size itself
+				if invalidSize(sz, targetSz) {
+					_ = dstWr.CloseWithError(ErrInvalidDelta)
+					return
+				}
+				if _, err := io.Copy(dstWr, io.LimitReader(deltaBuf, int64(sz))); err != nil {
+					_ = dstWr.CloseWithError(err)
+					return
+				}
+
+				remainingTargetSz -= sz
+			} else {
+				_ = dstWr.CloseWithError(ErrDeltaCmd)
+				return
+			}
+			if remainingTargetSz <= 0 {
+				_ = dstWr.Close()
+				return
+			}
+		}
+	}()
+
+	return dstRd, nil
+}
+
 func patchDelta(dst *bytes.Buffer, src, delta []byte) error {
 	if len(delta) < deltaSizeMin {
 		return ErrInvalidDelta
@@ -161,6 +287,25 @@ func decodeLEB128(input []byte) (uint, []byte) {
 	return num, input[sz:]
 }
 
+func decodeLEB128ByteReader(input io.ByteReader) (uint, error) {
+	var num, sz uint
+	for {
+		b, err := input.ReadByte()
+		if err != nil {
+			return 0, err
+		}
+
+		num |= (uint(b) & payload) << (sz * 7) // concats 7 bits chunks
+		sz++
+
+		if uint(b)&continuation == 0 {
+			break
+		}
+	}
+
+	return num, nil
+}
+
 const (
 	payload      = 0x7f // 0111 1111
 	continuation = 0x80 // 1000 0000
@@ -174,6 +319,40 @@ func isCopyFromDelta(cmd byte) bool {
 	return (cmd&0x80) == 0 && cmd != 0
 }
 
+func decodeOffsetByteReader(cmd byte, delta io.ByteReader) (uint, error) {
+	var offset uint
+	if (cmd & 0x01) != 0 {
+		next, err := delta.ReadByte()
+		if err != nil {
+			return 0, err
+		}
+		offset = uint(next)
+	}
+	if (cmd & 0x02) != 0 {
+		next, err := delta.ReadByte()
+		if err != nil {
+			return 0, err
+		}
+		offset |= uint(next) << 8
+	}
+	if (cmd & 0x04) != 0 {
+		next, err := delta.ReadByte()
+		if err != nil {
+			return 0, err
+		}
+		offset |= uint(next) << 16
+	}
+	if (cmd & 0x08) != 0 {
+		next, err := delta.ReadByte()
+		if err != nil {
+			return 0, err
+		}
+		offset |= uint(next) << 24
+	}
+
+	return offset, nil
+}
+
 func decodeOffset(cmd byte, delta []byte) (uint, []byte, error) {
 	var offset uint
 	if (cmd & 0x01) != 0 {
@@ -208,6 +387,36 @@ func decodeOffset(cmd byte, delta []byte) (uint, []byte, error) {
 	return offset, delta, nil
 }
 
+func decodeSizeByteReader(cmd byte, delta io.ByteReader) (uint, error) {
+	var sz uint
+	if (cmd & 0x10) != 0 {
+		next, err := delta.ReadByte()
+		if err != nil {
+			return 0, err
+		}
+		sz = uint(next)
+	}
+	if (cmd & 0x20) != 0 {
+		next, err := delta.ReadByte()
+		if err != nil {
+			return 0, err
+		}
+		sz |= uint(next) << 8
+	}
+	if (cmd & 0x40) != 0 {
+		next, err := delta.ReadByte()
+		if err != nil {
+			return 0, err
+		}
+		sz |= uint(next) << 16
+	}
+	if sz == 0 {
+		sz = 0x10000
+	}
+
+	return sz, nil
+}
+
 func decodeSize(cmd byte, delta []byte) (uint, []byte, error) {
 	var sz uint
 	if (cmd & 0x10) != 0 {
diff --git a/plumbing/format/packfile/scanner.go b/plumbing/format/packfile/scanner.go
index 6e6a68788..9ebb84a24 100644
--- a/plumbing/format/packfile/scanner.go
+++ b/plumbing/format/packfile/scanner.go
@@ -3,17 +3,16 @@ package packfile
 import (
 	"bufio"
 	"bytes"
-	"compress/zlib"
 	"fmt"
 	"hash"
 	"hash/crc32"
 	"io"
 	stdioutil "io/ioutil"
-	"sync"
 
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/utils/binary"
 	"github.com/go-git/go-git/v5/utils/ioutil"
+	"github.com/go-git/go-git/v5/utils/sync"
 )
 
 var (
@@ -114,7 +113,7 @@ func (s *Scanner) Header() (version, objects uint32, err error) {
 	return
 }
 
-// readSignature reads an returns the signature field in the packfile.
+// readSignature reads a returns the signature field in the packfile.
 func (s *Scanner) readSignature() ([]byte, error) {
 	var sig = make([]byte, 4)
 	if _, err := io.ReadFull(s.r, sig); err != nil {
@@ -320,29 +319,38 @@ func (s *Scanner) NextObject(w io.Writer) (written int64, crc32 uint32, err erro
 	return
 }
 
+// ReadObject returns a reader for the object content and an error
+func (s *Scanner) ReadObject() (io.ReadCloser, error) {
+	s.pendingObject = nil
+	zr, err := sync.GetZlibReader(s.r)
+
+	if err != nil {
+		return nil, fmt.Errorf("zlib reset error: %s", err)
+	}
+
+	return ioutil.NewReadCloserWithCloser(zr.Reader, func() error {
+		sync.PutZlibReader(zr)
+		return nil
+	}), nil
+}
+
 // ReadRegularObject reads and write a non-deltified object
 // from it zlib stream in an object entry in the packfile.
 func (s *Scanner) copyObject(w io.Writer) (n int64, err error) {
-	zr := zlibReaderPool.Get().(io.ReadCloser)
-	defer zlibReaderPool.Put(zr)
+	zr, err := sync.GetZlibReader(s.r)
+	defer sync.PutZlibReader(zr)
 
-	if err = zr.(zlib.Resetter).Reset(s.r, nil); err != nil {
+	if err != nil {
 		return 0, fmt.Errorf("zlib reset error: %s", err)
 	}
 
-	defer ioutil.CheckClose(zr, &err)
-	buf := byteSlicePool.Get().([]byte)
-	n, err = io.CopyBuffer(w, zr, buf)
-	byteSlicePool.Put(buf)
+	defer ioutil.CheckClose(zr.Reader, &err)
+	buf := sync.GetByteSlice()
+	n, err = io.CopyBuffer(w, zr.Reader, *buf)
+	sync.PutByteSlice(buf)
 	return
 }
 
-var byteSlicePool = sync.Pool{
-	New: func() interface{} {
-		return make([]byte, 32*1024)
-	},
-}
-
 // SeekFromStart sets a new offset from start, returns the old position before
 // the change.
 func (s *Scanner) SeekFromStart(offset int64) (previous int64, err error) {
@@ -372,9 +380,10 @@ func (s *Scanner) Checksum() (plumbing.Hash, error) {
 
 // Close reads the reader until io.EOF
 func (s *Scanner) Close() error {
-	buf := byteSlicePool.Get().([]byte)
-	_, err := io.CopyBuffer(stdioutil.Discard, s.r, buf)
-	byteSlicePool.Put(buf)
+	buf := sync.GetByteSlice()
+	_, err := io.CopyBuffer(stdioutil.Discard, s.r, *buf)
+	sync.PutByteSlice(buf)
+
 	return err
 }
 
@@ -384,13 +393,13 @@ func (s *Scanner) Flush() error {
 }
 
 // scannerReader has the following characteristics:
-// - Provides an io.SeekReader impl for bufio.Reader, when the underlying
-//   reader supports it.
-// - Keeps track of the current read position, for when the underlying reader
-//   isn't an io.SeekReader, but we still want to know the current offset.
-// - Writes to the hash writer what it reads, with the aid of a smaller buffer.
-//   The buffer helps avoid a performance penality for performing small writes
-//   to the crc32 hash writer.
+//   - Provides an io.SeekReader impl for bufio.Reader, when the underlying
+//     reader supports it.
+//   - Keeps track of the current read position, for when the underlying reader
+//     isn't an io.SeekReader, but we still want to know the current offset.
+//   - Writes to the hash writer what it reads, with the aid of a smaller buffer.
+//     The buffer helps avoid a performance penalty for performing small writes
+//     to the crc32 hash writer.
 type scannerReader struct {
 	reader io.Reader
 	crc    io.Writer
diff --git a/plumbing/hash.go b/plumbing/hash.go
index afc602a9e..2fab7593b 100644
--- a/plumbing/hash.go
+++ b/plumbing/hash.go
@@ -2,11 +2,12 @@ package plumbing
 
 import (
 	"bytes"
-	"crypto/sha1"
+	"crypto"
 	"encoding/hex"
-	"hash"
 	"sort"
 	"strconv"
+
+	"github.com/go-git/go-git/v5/plumbing/hash"
 )
 
 // Hash SHA1 hashed content
@@ -46,7 +47,7 @@ type Hasher struct {
 }
 
 func NewHasher(t ObjectType, size int64) Hasher {
-	h := Hasher{sha1.New()}
+	h := Hasher{hash.New(crypto.SHA1)}
 	h.Write(t.Bytes())
 	h.Write([]byte(" "))
 	h.Write([]byte(strconv.FormatInt(size, 10)))
diff --git a/plumbing/hash/hash.go b/plumbing/hash/hash.go
new file mode 100644
index 000000000..fe3bf7655
--- /dev/null
+++ b/plumbing/hash/hash.go
@@ -0,0 +1,59 @@
+// package hash provides a way for managing the
+// underlying hash implementations used across go-git.
+package hash
+
+import (
+	"crypto"
+	"fmt"
+	"hash"
+
+	"github.com/pjbgf/sha1cd/cgo"
+)
+
+// algos is a map of hash algorithms.
+var algos = map[crypto.Hash]func() hash.Hash{}
+
+func init() {
+	reset()
+}
+
+// reset resets the default algos value. Can be used after running tests
+// that registers new algorithms to avoid side effects.
+func reset() {
+	// For performance reasons the cgo version of the collision
+	// detection algorithm is being used.
+	algos[crypto.SHA1] = cgo.New
+}
+
+// RegisterHash allows for the hash algorithm used to be overriden.
+// This ensures the hash selection for go-git must be explicit, when
+// overriding the default value.
+func RegisterHash(h crypto.Hash, f func() hash.Hash) error {
+	if f == nil {
+		return fmt.Errorf("cannot register hash: f is nil")
+	}
+
+	switch h {
+	case crypto.SHA1:
+		algos[h] = f
+	default:
+		return fmt.Errorf("unsupported hash function: %v", h)
+	}
+	return nil
+}
+
+// Hash is the same as hash.Hash. This allows consumers
+// to not having to import this package alongside "hash".
+type Hash interface {
+	hash.Hash
+}
+
+// New returns a new Hash for the given hash function.
+// It panics if the hash function is not registered.
+func New(h crypto.Hash) Hash {
+	hh, ok := algos[h]
+	if !ok {
+		panic(fmt.Sprintf("hash algorithm not registered: %v", h))
+	}
+	return hh()
+}
diff --git a/plumbing/hash/hash_test.go b/plumbing/hash/hash_test.go
new file mode 100644
index 000000000..f70ad117e
--- /dev/null
+++ b/plumbing/hash/hash_test.go
@@ -0,0 +1,103 @@
+package hash
+
+import (
+	"crypto"
+	"crypto/sha1"
+	"crypto/sha512"
+	"encoding/hex"
+	"hash"
+	"strings"
+	"testing"
+)
+
+func TestRegisterHash(t *testing.T) {
+	// Reset default hash to avoid side effects.
+	defer reset()
+
+	tests := []struct {
+		name    string
+		hash    crypto.Hash
+		new     func() hash.Hash
+		wantErr string
+	}{
+		{
+			name: "sha1",
+			hash: crypto.SHA1,
+			new:  sha1.New,
+		},
+		{
+			name:    "sha1",
+			hash:    crypto.SHA1,
+			wantErr: "cannot register hash: f is nil",
+		},
+		{
+			name:    "sha512",
+			hash:    crypto.SHA512,
+			new:     sha512.New,
+			wantErr: "unsupported hash function",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := RegisterHash(tt.hash, tt.new)
+			if tt.wantErr == "" && err != nil {
+				t.Errorf("unexpected error: %v", err)
+			} else if tt.wantErr != "" && err == nil {
+				t.Errorf("expected error: %v got: nil", tt.wantErr)
+			} else if err != nil && !strings.Contains(err.Error(), tt.wantErr) {
+				t.Errorf("expected error: %v got: %v", tt.wantErr, err)
+			}
+		})
+	}
+}
+
+// Verifies that the SHA1 implementation used is collision-resistant
+// by default.
+func TestSha1Collision(t *testing.T) {
+	defer reset()
+
+	tests := []struct {
+		name    string
+		content string
+		hash    string
+		before  func()
+	}{
+		{
+			name:    "sha-mbles-1: with collision detection",
+			content: "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",
+			hash:    "4f3d9be4a472c4dae83c6314aa6c36a064c1fd14",
+		},
+		{
+			name:    "sha-mbles-1: with default SHA1",
+			content: "99040d047fe81780012000ff4b65792069732070617274206f66206120636f6c6c6973696f6e212049742773206120747261702179c61af0afcc054515d9274e7307624b1dc7fb23988bb8de8b575dba7b9eab31c1674b6d974378a827732ff5851c76a2e60772b5a47ce1eac40bb993c12d8c70e24a4f8d5fcdedc1b32c9cf19e31af2429759d42e4dfdb31719f587623ee552939b6dcdc459fca53553b70f87ede30a247ea3af6c759a2f20b320d760db64ff479084fd3ccb3cdd48362d96a9c430617caff6c36c637e53fde28417f626fec54ed7943a46e5f5730f2bb38fb1df6e0090010d00e24ad78bf92641993608e8d158a789f34c46fe1e6027f35a4cbfb827076c50eca0e8b7cca69bb2c2b790259f9bf9570dd8d4437a3115faff7c3cac09ad25266055c27104755178eaeff825a2caa2acfb5de64ce7641dc59a541a9fc9c756756e2e23dc713c8c24c9790aa6b0e38a7f55f14452a1ca2850ddd9562fd9a18ad42496aa97008f74672f68ef461eb88b09933d626b4f918749cc027fddd6c425fc4216835d0134d15285bab2cb784a4f7cbb4fb514d4bf0f6237cf00a9e9f132b9a066e6fd17f6c42987478586ff651af96747fb426b9872b9a88e4063f59bb334cc00650f83a80c42751b71974d300fc2819a2e8f1e32c1b51cb18e6bfc4db9baef675d4aaf5b1574a047f8f6dd2ec153a93412293974d928f88ced9363cfef97ce2e742bf34c96b8ef3875676fea5cca8e5f7dea0bab2413d4de00ee71ee01f162bdb6d1eafd925e6aebaae6a354ef17cf205a404fbdb12fc454d41fdd95cf2459664a2ad032d1da60a73264075d7f1e0d6c1403ae7a0d861df3fe5707188dd5e07d1589b9f8b6630553f8fc352b3e0c27da80bddba4c64020d",
+			hash:    "8ac60ba76f1999a1ab70223f225aefdc78d4ddc0",
+			before: func() {
+				RegisterHash(crypto.SHA1, sha1.New)
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if tt.before != nil {
+				tt.before()
+			}
+
+			h := New(crypto.SHA1)
+			data, err := hex.DecodeString(tt.content)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			h.Reset()
+			h.Write(data)
+			sum := h.Sum(nil)
+			got := hex.EncodeToString(sum)
+
+			if tt.hash != got {
+				t.Errorf("\n   got: %q\nwanted: %q", got, tt.hash)
+			}
+		})
+	}
+}
diff --git a/plumbing/memory.go b/plumbing/memory.go
index 21337cc0d..6d11271dd 100644
--- a/plumbing/memory.go
+++ b/plumbing/memory.go
@@ -25,13 +25,13 @@ func (o *MemoryObject) Hash() Hash {
 	return o.h
 }
 
-// Type return the ObjectType
+// Type returns the ObjectType
 func (o *MemoryObject) Type() ObjectType { return o.t }
 
 // SetType sets the ObjectType
 func (o *MemoryObject) SetType(t ObjectType) { o.t = t }
 
-// Size return the size of the object
+// Size returns the size of the object
 func (o *MemoryObject) Size() int64 { return o.sz }
 
 // SetSize set the object size, a content of the given size should be written
diff --git a/plumbing/object/change.go b/plumbing/object/change.go
index 8b119bc9c..3c619df86 100644
--- a/plumbing/object/change.go
+++ b/plumbing/object/change.go
@@ -39,7 +39,7 @@ func (c *Change) Action() (merkletrie.Action, error) {
 	return merkletrie.Modify, nil
 }
 
-// Files return the files before and after a change.
+// Files returns the files before and after a change.
 // For insertions from will be nil. For deletions to will be nil.
 func (c *Change) Files() (from, to *File, err error) {
 	action, err := c.Action()
diff --git a/plumbing/object/change_adaptor.go b/plumbing/object/change_adaptor.go
index f70118828..b96ee84d9 100644
--- a/plumbing/object/change_adaptor.go
+++ b/plumbing/object/change_adaptor.go
@@ -16,11 +16,11 @@ func newChange(c merkletrie.Change) (*Change, error) {
 
 	var err error
 	if ret.From, err = newChangeEntry(c.From); err != nil {
-		return nil, fmt.Errorf("From field: %s", err)
+		return nil, fmt.Errorf("from field: %s", err)
 	}
 
 	if ret.To, err = newChangeEntry(c.To); err != nil {
-		return nil, fmt.Errorf("To field: %s", err)
+		return nil, fmt.Errorf("to field: %s", err)
 	}
 
 	return ret, nil
diff --git a/plumbing/object/commit.go b/plumbing/object/commit.go
index 7a1b8e5ae..d2f718408 100644
--- a/plumbing/object/commit.go
+++ b/plumbing/object/commit.go
@@ -1,7 +1,6 @@
 package object
 
 import (
-	"bufio"
 	"bytes"
 	"context"
 	"errors"
@@ -14,6 +13,7 @@ import (
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/plumbing/storer"
 	"github.com/go-git/go-git/v5/utils/ioutil"
+	"github.com/go-git/go-git/v5/utils/sync"
 )
 
 const (
@@ -180,9 +180,8 @@ func (c *Commit) Decode(o plumbing.EncodedObject) (err error) {
 	}
 	defer ioutil.CheckClose(reader, &err)
 
-	r := bufPool.Get().(*bufio.Reader)
-	defer bufPool.Put(r)
-	r.Reset(reader)
+	r := sync.GetBufioReader(reader)
+	defer sync.PutBufioReader(r)
 
 	var message bool
 	var pgpsig bool
diff --git a/plumbing/object/common.go b/plumbing/object/common.go
deleted file mode 100644
index 3591f5f0a..000000000
--- a/plumbing/object/common.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package object
-
-import (
-	"bufio"
-	"sync"
-)
-
-var bufPool = sync.Pool{
-	New: func() interface{} {
-		return bufio.NewReader(nil)
-	},
-}
diff --git a/plumbing/object/patch.go b/plumbing/object/patch.go
index 56b62c191..06bc35bbc 100644
--- a/plumbing/object/patch.go
+++ b/plumbing/object/patch.go
@@ -96,10 +96,6 @@ func filePatchWithContext(ctx context.Context, c *Change) (fdiff.FilePatch, erro
 
 }
 
-func filePatch(c *Change) (fdiff.FilePatch, error) {
-	return filePatchWithContext(context.Background(), c)
-}
-
 func fileContent(f *File) (content string, isBinary bool, err error) {
 	if f == nil {
 		return
diff --git a/plumbing/object/rename.go b/plumbing/object/rename.go
index 7fed72c2f..0394613ff 100644
--- a/plumbing/object/rename.go
+++ b/plumbing/object/rename.go
@@ -403,10 +403,16 @@ func min(a, b int) int {
 	return b
 }
 
+const maxMatrixSize = 10000
+
 func buildSimilarityMatrix(srcs, dsts []*Change, renameScore int) (similarityMatrix, error) {
 	// Allocate for the worst-case scenario where every pair has a score
 	// that we need to consider. We might not need that many.
-	matrix := make(similarityMatrix, 0, len(srcs)*len(dsts))
+	matrixSize := len(srcs) * len(dsts)
+	if matrixSize > maxMatrixSize {
+		matrixSize = maxMatrixSize
+	}
+	matrix := make(similarityMatrix, 0, matrixSize)
 	srcSizes := make([]int64, len(srcs))
 	dstSizes := make([]int64, len(dsts))
 	dstTooLarge := make(map[int]bool)
diff --git a/plumbing/object/tag.go b/plumbing/object/tag.go
index 216010d91..84066f768 100644
--- a/plumbing/object/tag.go
+++ b/plumbing/object/tag.go
@@ -1,7 +1,6 @@
 package object
 
 import (
-	"bufio"
 	"bytes"
 	"fmt"
 	"io"
@@ -13,6 +12,7 @@ import (
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/plumbing/storer"
 	"github.com/go-git/go-git/v5/utils/ioutil"
+	"github.com/go-git/go-git/v5/utils/sync"
 )
 
 // Tag represents an annotated tag object. It points to a single git object of
@@ -93,9 +93,9 @@ func (t *Tag) Decode(o plumbing.EncodedObject) (err error) {
 	}
 	defer ioutil.CheckClose(reader, &err)
 
-	r := bufPool.Get().(*bufio.Reader)
-	defer bufPool.Put(r)
-	r.Reset(reader)
+	r := sync.GetBufioReader(reader)
+	defer sync.PutBufioReader(r)
+
 	for {
 		var line []byte
 		line, err = r.ReadBytes('\n')
diff --git a/plumbing/object/tree.go b/plumbing/object/tree.go
index 5e6378ca4..e9f7666b8 100644
--- a/plumbing/object/tree.go
+++ b/plumbing/object/tree.go
@@ -1,7 +1,6 @@
 package object
 
 import (
-	"bufio"
 	"context"
 	"errors"
 	"fmt"
@@ -14,6 +13,7 @@ import (
 	"github.com/go-git/go-git/v5/plumbing/filemode"
 	"github.com/go-git/go-git/v5/plumbing/storer"
 	"github.com/go-git/go-git/v5/utils/ioutil"
+	"github.com/go-git/go-git/v5/utils/sync"
 )
 
 const (
@@ -230,9 +230,9 @@ func (t *Tree) Decode(o plumbing.EncodedObject) (err error) {
 	}
 	defer ioutil.CheckClose(reader, &err)
 
-	r := bufPool.Get().(*bufio.Reader)
-	defer bufPool.Put(r)
-	r.Reset(reader)
+	r := sync.GetBufioReader(reader)
+	defer sync.PutBufioReader(r)
+
 	for {
 		str, err := r.ReadString(' ')
 		if err != nil {
diff --git a/plumbing/object/treenoder.go b/plumbing/object/treenoder.go
index b4891b957..6e7b334cb 100644
--- a/plumbing/object/treenoder.go
+++ b/plumbing/object/treenoder.go
@@ -38,6 +38,10 @@ func NewTreeRootNode(t *Tree) noder.Noder {
 	}
 }
 
+func (t *treeNoder) Skip() bool {
+	return false
+}
+
 func (t *treeNoder) isRoot() bool {
 	return t.name == ""
 }
diff --git a/plumbing/protocol/packp/capability/capability.go b/plumbing/protocol/packp/capability/capability.go
index 8d6a56f53..b52e8a49d 100644
--- a/plumbing/protocol/packp/capability/capability.go
+++ b/plumbing/protocol/packp/capability/capability.go
@@ -1,6 +1,11 @@
 // Package capability defines the server and client capabilities.
 package capability
 
+import (
+	"fmt"
+	"os"
+)
+
 // Capability describes a server or client capability.
 type Capability string
 
@@ -238,7 +243,15 @@ const (
 	Filter Capability = "filter"
 )
 
-const DefaultAgent = "go-git/4.x"
+const userAgent = "go-git/5.x"
+
+// DefaultAgent provides the user agent string.
+func DefaultAgent() string {
+	if envUserAgent, ok := os.LookupEnv("GO_GIT_USER_AGENT_EXTRA"); ok {
+		return fmt.Sprintf("%s %s", userAgent, envUserAgent)
+	}
+	return userAgent
+}
 
 var known = map[Capability]bool{
 	MultiACK: true, MultiACKDetailed: true, NoDone: true, ThinPack: true,
diff --git a/plumbing/protocol/packp/capability/capability_test.go b/plumbing/protocol/packp/capability/capability_test.go
new file mode 100644
index 000000000..f1fd0282a
--- /dev/null
+++ b/plumbing/protocol/packp/capability/capability_test.go
@@ -0,0 +1,22 @@
+package capability
+
+import (
+	"fmt"
+	"os"
+
+	check "gopkg.in/check.v1"
+)
+
+var _ = check.Suite(&SuiteCapabilities{})
+
+func (s *SuiteCapabilities) TestDefaultAgent(c *check.C) {
+	os.Unsetenv("GO_GIT_USER_AGENT_EXTRA")
+	ua := DefaultAgent()
+	c.Assert(ua, check.Equals, userAgent)
+}
+
+func (s *SuiteCapabilities) TestEnvAgent(c *check.C) {
+	os.Setenv("GO_GIT_USER_AGENT_EXTRA", "abc xyz")
+	ua := DefaultAgent()
+	c.Assert(ua, check.Equals, fmt.Sprintf("%s %s", userAgent, "abc xyz"))
+}
diff --git a/plumbing/protocol/packp/capability/list.go b/plumbing/protocol/packp/capability/list.go
index f41ec799c..553d81cbe 100644
--- a/plumbing/protocol/packp/capability/list.go
+++ b/plumbing/protocol/packp/capability/list.go
@@ -86,7 +86,9 @@ func (l *List) Get(capability Capability) []string {
 
 // Set sets a capability removing the previous values
 func (l *List) Set(capability Capability, values ...string) error {
-	delete(l.m, capability)
+	if _, ok := l.m[capability]; ok {
+		l.m[capability].Values = l.m[capability].Values[:0]
+	}
 	return l.Add(capability, values...)
 }
 
diff --git a/plumbing/protocol/packp/capability/list_test.go b/plumbing/protocol/packp/capability/list_test.go
index 61b0b13be..71181cbc9 100644
--- a/plumbing/protocol/packp/capability/list_test.go
+++ b/plumbing/protocol/packp/capability/list_test.go
@@ -122,6 +122,17 @@ func (s *SuiteCapabilities) TestSetEmpty(c *check.C) {
 	c.Assert(cap.Get(Agent), check.HasLen, 1)
 }
 
+func (s *SuiteCapabilities) TestSetDuplicate(c *check.C) {
+	cap := NewList()
+	err := cap.Set(Agent, "baz")
+	c.Assert(err, check.IsNil)
+
+	err = cap.Set(Agent, "bar")
+	c.Assert(err, check.IsNil)
+
+	c.Assert(cap.String(), check.Equals, "agent=bar")
+}
+
 func (s *SuiteCapabilities) TestGetEmpty(c *check.C) {
 	cap := NewList()
 	c.Assert(cap.Get(Agent), check.HasLen, 0)
diff --git a/plumbing/protocol/packp/common.go b/plumbing/protocol/packp/common.go
index ab07ac8f7..fef50a450 100644
--- a/plumbing/protocol/packp/common.go
+++ b/plumbing/protocol/packp/common.go
@@ -19,7 +19,6 @@ var (
 	// common
 	sp  = []byte(" ")
 	eol = []byte("\n")
-	eq  = []byte{'='}
 
 	// advertised-refs
 	null       = []byte("\x00")
diff --git a/plumbing/protocol/packp/srvresp.go b/plumbing/protocol/packp/srvresp.go
index b3a7ee804..8cd0a7247 100644
--- a/plumbing/protocol/packp/srvresp.go
+++ b/plumbing/protocol/packp/srvresp.go
@@ -21,11 +21,6 @@ type ServerResponse struct {
 // Decode decodes the response into the struct, isMultiACK should be true, if
 // the request was done with multi_ack or multi_ack_detailed capabilities.
 func (r *ServerResponse) Decode(reader *bufio.Reader, isMultiACK bool) error {
-	// TODO: implement support for multi_ack or multi_ack_detailed responses
-	if isMultiACK {
-		return errors.New("multi_ack and multi_ack_detailed are not supported")
-	}
-
 	s := pktline.NewScanner(reader)
 
 	for s.Scan() {
@@ -48,7 +43,23 @@ func (r *ServerResponse) Decode(reader *bufio.Reader, isMultiACK bool) error {
 		}
 	}
 
-	return s.Err()
+	// isMultiACK is true when the remote server advertises the related
+	// capabilities when they are not in transport.UnsupportedCapabilities.
+	//
+	// Users may decide to remove multi_ack and multi_ack_detailed from the
+	// unsupported capabilities list, which allows them to do initial clones
+	// from Azure DevOps.
+	//
+	// Follow-up fetches may error, therefore errors are wrapped with additional
+	// information highlighting that this capabilities are not supported by go-git.
+	//
+	// TODO: Implement support for multi_ack or multi_ack_detailed responses.
+	err := s.Err()
+	if err != nil && isMultiACK {
+		return fmt.Errorf("multi_ack and multi_ack_detailed are not supported: %w", err)
+	}
+
+	return err
 }
 
 // stopReading detects when a valid command such as ACK or NAK is found to be
@@ -113,8 +124,9 @@ func (r *ServerResponse) decodeACKLine(line []byte) error {
 }
 
 // Encode encodes the ServerResponse into a writer.
-func (r *ServerResponse) Encode(w io.Writer) error {
-	if len(r.ACKs) > 1 {
+func (r *ServerResponse) Encode(w io.Writer, isMultiACK bool) error {
+	if len(r.ACKs) > 1 && !isMultiACK {
+		// For further information, refer to comments in the Decode func above.
 		return errors.New("multi_ack and multi_ack_detailed are not supported")
 	}
 
diff --git a/plumbing/protocol/packp/srvresp_test.go b/plumbing/protocol/packp/srvresp_test.go
index 02fab424e..aa0af528a 100644
--- a/plumbing/protocol/packp/srvresp_test.go
+++ b/plumbing/protocol/packp/srvresp_test.go
@@ -72,8 +72,21 @@ func (s *ServerResponseSuite) TestDecodeMalformed(c *C) {
 	c.Assert(err, NotNil)
 }
 
+// multi_ack isn't fully implemented, this ensures that Decode ignores that fact,
+// as in some circumstances that's OK to assume so.
+//
+// TODO: Review as part of multi_ack implementation.
 func (s *ServerResponseSuite) TestDecodeMultiACK(c *C) {
+	raw := "" +
+		"0031ACK 1111111111111111111111111111111111111111\n" +
+		"0031ACK 6ecf0ef2c2dffb796033e5a02219af86ec6584e5\n" +
+		"00080PACK\n"
+
 	sr := &ServerResponse{}
-	err := sr.Decode(bufio.NewReader(bytes.NewBuffer(nil)), true)
-	c.Assert(err, NotNil)
+	err := sr.Decode(bufio.NewReader(bytes.NewBufferString(raw)), true)
+	c.Assert(err, IsNil)
+
+	c.Assert(sr.ACKs, HasLen, 2)
+	c.Assert(sr.ACKs[0], Equals, plumbing.NewHash("1111111111111111111111111111111111111111"))
+	c.Assert(sr.ACKs[1], Equals, plumbing.NewHash("6ecf0ef2c2dffb796033e5a02219af86ec6584e5"))
 }
diff --git a/plumbing/protocol/packp/ulreq.go b/plumbing/protocol/packp/ulreq.go
index ddec06e99..344f8c7e3 100644
--- a/plumbing/protocol/packp/ulreq.go
+++ b/plumbing/protocol/packp/ulreq.go
@@ -95,7 +95,7 @@ func NewUploadRequestFromCapabilities(adv *capability.List) *UploadRequest {
 	}
 
 	if adv.Supports(capability.Agent) {
-		r.Capabilities.Set(capability.Agent, capability.DefaultAgent)
+		r.Capabilities.Set(capability.Agent, capability.DefaultAgent())
 	}
 
 	return r
diff --git a/plumbing/protocol/packp/ulreq_test.go b/plumbing/protocol/packp/ulreq_test.go
index 0b3b61653..2797a4ea5 100644
--- a/plumbing/protocol/packp/ulreq_test.go
+++ b/plumbing/protocol/packp/ulreq_test.go
@@ -25,7 +25,7 @@ func (s *UlReqSuite) TestNewUploadRequestFromCapabilities(c *C) {
 
 	r := NewUploadRequestFromCapabilities(cap)
 	c.Assert(r.Capabilities.String(), Equals,
-		"multi_ack_detailed side-band-64k thin-pack ofs-delta agent=go-git/4.x",
+		"multi_ack_detailed side-band-64k thin-pack ofs-delta agent=go-git/5.x",
 	)
 }
 
diff --git a/plumbing/protocol/packp/updreq.go b/plumbing/protocol/packp/updreq.go
index 4d927d8b8..8f39b39cb 100644
--- a/plumbing/protocol/packp/updreq.go
+++ b/plumbing/protocol/packp/updreq.go
@@ -19,6 +19,7 @@ var (
 type ReferenceUpdateRequest struct {
 	Capabilities *capability.List
 	Commands     []*Command
+	Options      []*Option
 	Shallow      *plumbing.Hash
 	// Packfile contains an optional packfile reader.
 	Packfile io.ReadCloser
@@ -58,7 +59,7 @@ func NewReferenceUpdateRequestFromCapabilities(adv *capability.List) *ReferenceU
 	r := NewReferenceUpdateRequest()
 
 	if adv.Supports(capability.Agent) {
-		r.Capabilities.Set(capability.Agent, capability.DefaultAgent)
+		r.Capabilities.Set(capability.Agent, capability.DefaultAgent())
 	}
 
 	if adv.Supports(capability.ReportStatus) {
@@ -86,9 +87,9 @@ type Action string
 
 const (
 	Create  Action = "create"
-	Update         = "update"
-	Delete         = "delete"
-	Invalid        = "invalid"
+	Update  Action = "update"
+	Delete  Action = "delete"
+	Invalid Action = "invalid"
 )
 
 type Command struct {
@@ -120,3 +121,8 @@ func (c *Command) validate() error {
 
 	return nil
 }
+
+type Option struct {
+	Key   string
+	Value string
+}
diff --git a/plumbing/protocol/packp/updreq_encode.go b/plumbing/protocol/packp/updreq_encode.go
index 2545e935e..1205cfaf1 100644
--- a/plumbing/protocol/packp/updreq_encode.go
+++ b/plumbing/protocol/packp/updreq_encode.go
@@ -9,10 +9,6 @@ import (
 	"github.com/go-git/go-git/v5/plumbing/protocol/packp/capability"
 )
 
-var (
-	zeroHashString = plumbing.ZeroHash.String()
-)
-
 // Encode writes the ReferenceUpdateRequest encoding to the stream.
 func (req *ReferenceUpdateRequest) Encode(w io.Writer) error {
 	if err := req.validate(); err != nil {
@@ -29,6 +25,12 @@ func (req *ReferenceUpdateRequest) Encode(w io.Writer) error {
 		return err
 	}
 
+	if req.Capabilities.Supports(capability.PushOptions) {
+		if err := req.encodeOptions(e, req.Options); err != nil {
+			return err
+		}
+	}
+
 	if req.Packfile != nil {
 		if _, err := io.Copy(w, req.Packfile); err != nil {
 			return err
@@ -73,3 +75,15 @@ func formatCommand(cmd *Command) string {
 	n := cmd.New.String()
 	return fmt.Sprintf("%s %s %s", o, n, cmd.Name)
 }
+
+func (req *ReferenceUpdateRequest) encodeOptions(e *pktline.Encoder,
+	opts []*Option) error {
+
+	for _, opt := range opts {
+		if err := e.Encodef("%s=%s", opt.Key, opt.Value); err != nil {
+			return err
+		}
+	}
+
+	return e.Flush()
+}
diff --git a/plumbing/protocol/packp/updreq_encode_test.go b/plumbing/protocol/packp/updreq_encode_test.go
index 5ad2b1bb7..4370b794f 100644
--- a/plumbing/protocol/packp/updreq_encode_test.go
+++ b/plumbing/protocol/packp/updreq_encode_test.go
@@ -5,9 +5,11 @@ import (
 
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/plumbing/format/pktline"
+	"github.com/go-git/go-git/v5/plumbing/protocol/packp/capability"
 
-	. "gopkg.in/check.v1"
 	"io/ioutil"
+
+	. "gopkg.in/check.v1"
 )
 
 type UpdReqEncodeSuite struct{}
@@ -142,3 +144,48 @@ func (s *UpdReqEncodeSuite) TestWithPackfile(c *C) {
 
 	s.testEncode(c, r, expected)
 }
+
+func (s *UpdReqEncodeSuite) TestPushOptions(c *C) {
+	hash1 := plumbing.NewHash("1ecf0ef2c2dffb796033e5a02219af86ec6584e5")
+	hash2 := plumbing.NewHash("2ecf0ef2c2dffb796033e5a02219af86ec6584e5")
+	name := plumbing.ReferenceName("myref")
+
+	r := NewReferenceUpdateRequest()
+	r.Capabilities.Set(capability.PushOptions)
+	r.Commands = []*Command{
+		{Name: name, Old: hash1, New: hash2},
+	}
+	r.Options = []*Option{
+		{Key: "SomeKey", Value: "SomeValue"},
+		{Key: "AnotherKey", Value: "AnotherValue"},
+	}
+
+	expected := pktlines(c,
+		"1ecf0ef2c2dffb796033e5a02219af86ec6584e5 2ecf0ef2c2dffb796033e5a02219af86ec6584e5 myref\x00push-options",
+		pktline.FlushString,
+		"SomeKey=SomeValue",
+		"AnotherKey=AnotherValue",
+		pktline.FlushString,
+	)
+
+	s.testEncode(c, r, expected)
+}
+
+func (s *UpdReqEncodeSuite) TestPushAtomic(c *C) {
+	hash1 := plumbing.NewHash("1ecf0ef2c2dffb796033e5a02219af86ec6584e5")
+	hash2 := plumbing.NewHash("2ecf0ef2c2dffb796033e5a02219af86ec6584e5")
+	name := plumbing.ReferenceName("myref")
+
+	r := NewReferenceUpdateRequest()
+	r.Capabilities.Set(capability.Atomic)
+	r.Commands = []*Command{
+		{Name: name, Old: hash1, New: hash2},
+	}
+
+	expected := pktlines(c,
+		"1ecf0ef2c2dffb796033e5a02219af86ec6584e5 2ecf0ef2c2dffb796033e5a02219af86ec6584e5 myref\x00atomic",
+		pktline.FlushString,
+	)
+
+	s.testEncode(c, r, expected)
+}
diff --git a/plumbing/protocol/packp/updreq_test.go b/plumbing/protocol/packp/updreq_test.go
index c4ccbaf64..80e03fbe7 100644
--- a/plumbing/protocol/packp/updreq_test.go
+++ b/plumbing/protocol/packp/updreq_test.go
@@ -23,14 +23,14 @@ func (s *UpdReqSuite) TestNewReferenceUpdateRequestFromCapabilities(c *C) {
 
 	r := NewReferenceUpdateRequestFromCapabilities(cap)
 	c.Assert(r.Capabilities.String(), Equals,
-		"agent=go-git/4.x report-status",
+		"agent=go-git/5.x report-status",
 	)
 
 	cap = capability.NewList()
 	cap.Set(capability.Agent, "foo")
 
 	r = NewReferenceUpdateRequestFromCapabilities(cap)
-	c.Assert(r.Capabilities.String(), Equals, "agent=go-git/4.x")
+	c.Assert(r.Capabilities.String(), Equals, "agent=go-git/5.x")
 
 	cap = capability.NewList()
 
diff --git a/plumbing/protocol/packp/uppackreq_test.go b/plumbing/protocol/packp/uppackreq_test.go
index f723e3cc7..5a6eb2cc8 100644
--- a/plumbing/protocol/packp/uppackreq_test.go
+++ b/plumbing/protocol/packp/uppackreq_test.go
@@ -18,7 +18,7 @@ func (s *UploadPackRequestSuite) TestNewUploadPackRequestFromCapabilities(c *C)
 	cap.Set(capability.Agent, "foo")
 
 	r := NewUploadPackRequestFromCapabilities(cap)
-	c.Assert(r.Capabilities.String(), Equals, "agent=go-git/4.x")
+	c.Assert(r.Capabilities.String(), Equals, "agent=go-git/5.x")
 }
 
 func (s *UploadPackRequestSuite) TestIsEmpty(c *C) {
diff --git a/plumbing/protocol/packp/uppackresp.go b/plumbing/protocol/packp/uppackresp.go
index a9a7192ea..a485cb7b2 100644
--- a/plumbing/protocol/packp/uppackresp.go
+++ b/plumbing/protocol/packp/uppackresp.go
@@ -24,7 +24,6 @@ type UploadPackResponse struct {
 	r          io.ReadCloser
 	isShallow  bool
 	isMultiACK bool
-	isOk       bool
 }
 
 // NewUploadPackResponse create a new UploadPackResponse instance, the request
@@ -79,7 +78,7 @@ func (r *UploadPackResponse) Encode(w io.Writer) (err error) {
 		}
 	}
 
-	if err := r.ServerResponse.Encode(w); err != nil {
+	if err := r.ServerResponse.Encode(w, r.isMultiACK); err != nil {
 		return err
 	}
 
diff --git a/plumbing/protocol/packp/uppackresp_test.go b/plumbing/protocol/packp/uppackresp_test.go
index 260dc5748..3f87804a5 100644
--- a/plumbing/protocol/packp/uppackresp_test.go
+++ b/plumbing/protocol/packp/uppackresp_test.go
@@ -59,6 +59,10 @@ func (s *UploadPackResponseSuite) TestDecodeMalformed(c *C) {
 	c.Assert(err, NotNil)
 }
 
+// multi_ack isn't fully implemented, this ensures that Decode ignores that fact,
+// as in some circumstances that's OK to assume so.
+//
+// TODO: Review as part of multi_ack implementation.
 func (s *UploadPackResponseSuite) TestDecodeMultiACK(c *C) {
 	req := NewUploadPackRequest()
 	req.Capabilities.Set(capability.MultiACK)
@@ -67,7 +71,7 @@ func (s *UploadPackResponseSuite) TestDecodeMultiACK(c *C) {
 	defer res.Close()
 
 	err := res.Decode(ioutil.NopCloser(bytes.NewBuffer(nil)))
-	c.Assert(err, NotNil)
+	c.Assert(err, IsNil)
 }
 
 func (s *UploadPackResponseSuite) TestReadNoDecode(c *C) {
diff --git a/plumbing/reference.go b/plumbing/reference.go
index 08e908f1f..eef11e827 100644
--- a/plumbing/reference.go
+++ b/plumbing/reference.go
@@ -168,22 +168,22 @@ func NewHashReference(n ReferenceName, h Hash) *Reference {
 	}
 }
 
-// Type return the type of a reference
+// Type returns the type of a reference
 func (r *Reference) Type() ReferenceType {
 	return r.t
 }
 
-// Name return the name of a reference
+// Name returns the name of a reference
 func (r *Reference) Name() ReferenceName {
 	return r.n
 }
 
-// Hash return the hash of a hash reference
+// Hash returns the hash of a hash reference
 func (r *Reference) Hash() Hash {
 	return r.h
 }
 
-// Target return the target of a symbolic reference
+// Target returns the target of a symbolic reference
 func (r *Reference) Target() ReferenceName {
 	return r.target
 }
@@ -204,6 +204,21 @@ func (r *Reference) Strings() [2]string {
 }
 
 func (r *Reference) String() string {
-	s := r.Strings()
-	return fmt.Sprintf("%s %s", s[1], s[0])
+	ref := ""
+	switch r.Type() {
+	case HashReference:
+		ref = r.Hash().String()
+	case SymbolicReference:
+		ref = symrefPrefix + r.Target().String()
+	default:
+		return ""
+	}
+
+	name := r.Name().String()
+	var v strings.Builder
+	v.Grow(len(ref) + len(name) + 1)
+	v.WriteString(ref)
+	v.WriteString(" ")
+	v.WriteString(name)
+	return v.String()
 }
diff --git a/plumbing/reference_test.go b/plumbing/reference_test.go
index b3ccf5340..e69076ff6 100644
--- a/plumbing/reference_test.go
+++ b/plumbing/reference_test.go
@@ -1,6 +1,10 @@
 package plumbing
 
-import . "gopkg.in/check.v1"
+import (
+	"testing"
+
+	. "gopkg.in/check.v1"
+)
 
 type ReferenceSuite struct{}
 
@@ -98,3 +102,21 @@ func (s *ReferenceSuite) TestIsTag(c *C) {
 	r := ReferenceName("refs/tags/v3.1.")
 	c.Assert(r.IsTag(), Equals, true)
 }
+
+func benchMarkReferenceString(r *Reference, b *testing.B) {
+	for n := 0; n < b.N; n++ {
+		r.String()
+	}
+}
+
+func BenchmarkReferenceStringSymbolic(b *testing.B) {
+	benchMarkReferenceString(NewSymbolicReference("v3.1.1", "refs/tags/v3.1.1"), b)
+}
+
+func BenchmarkReferenceStringHash(b *testing.B) {
+	benchMarkReferenceString(NewHashReference("v3.1.1", NewHash("6ecf0ef2c2dffb796033e5a02219af86ec6584e5")), b)
+}
+
+func BenchmarkReferenceStringInvalid(b *testing.B) {
+	benchMarkReferenceString(&Reference{}, b)
+}
diff --git a/plumbing/revlist/revlist_test.go b/plumbing/revlist/revlist_test.go
index a1ee504e8..9f2f93b53 100644
--- a/plumbing/revlist/revlist_test.go
+++ b/plumbing/revlist/revlist_test.go
@@ -55,12 +55,6 @@ func (s *RevListSuite) SetUpTest(c *C) {
 	s.Storer = sto
 }
 
-func (s *RevListSuite) commit(c *C, h plumbing.Hash) *object.Commit {
-	commit, err := object.GetCommit(s.Storer, h)
-	c.Assert(err, IsNil)
-	return commit
-}
-
 func (s *RevListSuite) TestRevListObjects_Submodules(c *C) {
 	submodules := map[string]bool{
 		"6ecf0ef2c2dffb796033e5a02219af86ec6584e5": true,
diff --git a/plumbing/storer/object.go b/plumbing/storer/object.go
index dfe309db1..d8a9c27a6 100644
--- a/plumbing/storer/object.go
+++ b/plumbing/storer/object.go
@@ -52,8 +52,8 @@ type DeltaObjectStorer interface {
 	DeltaObject(plumbing.ObjectType, plumbing.Hash) (plumbing.EncodedObject, error)
 }
 
-// Transactioner is a optional method for ObjectStorer, it enable transaction
-// base write and read operations in the storage
+// Transactioner is a optional method for ObjectStorer, it enables transactional read and write
+// operations.
 type Transactioner interface {
 	// Begin starts a transaction.
 	Begin() Transaction
@@ -87,8 +87,8 @@ type PackedObjectStorer interface {
 	DeleteOldObjectPackAndIndex(plumbing.Hash, time.Time) error
 }
 
-// PackfileWriter is a optional method for ObjectStorer, it enable direct write
-// of packfile to the storage
+// PackfileWriter is an optional method for ObjectStorer, it enables directly writing
+// a packfile to storage.
 type PackfileWriter interface {
 	// PackfileWriter returns a writer for writing a packfile to the storage
 	//
diff --git a/plumbing/transport/client/client_test.go b/plumbing/transport/client/client_test.go
index 9ebe113b1..92db525a5 100644
--- a/plumbing/transport/client/client_test.go
+++ b/plumbing/transport/client/client_test.go
@@ -1,7 +1,6 @@
 package client
 
 import (
-	"fmt"
 	"net/http"
 	"testing"
 
@@ -68,7 +67,3 @@ func (*dummyClient) NewReceivePackSession(*transport.Endpoint, transport.AuthMet
 	transport.ReceivePackSession, error) {
 	return nil, nil
 }
-
-func typeAsString(v interface{}) string {
-	return fmt.Sprintf("%T", v)
-}
diff --git a/plumbing/transport/common.go b/plumbing/transport/common.go
index a9ee2caee..a2a78f028 100644
--- a/plumbing/transport/common.go
+++ b/plumbing/transport/common.go
@@ -112,7 +112,7 @@ type Endpoint struct {
 	Port int
 	// Path is the repository path.
 	Path string
-	// InsecureSkipTLS skips ssl verify if protocal is https
+	// InsecureSkipTLS skips ssl verify if protocol is https
 	InsecureSkipTLS bool
 	// CaBundle specify additional ca bundle with system cert pool
 	CaBundle []byte
diff --git a/plumbing/transport/git/common.go b/plumbing/transport/git/common.go
index 306aae261..c18d600c2 100644
--- a/plumbing/transport/git/common.go
+++ b/plumbing/transport/git/common.go
@@ -77,14 +77,14 @@ func (c *command) StderrPipe() (io.Reader, error) {
 	return nil, nil
 }
 
-// StdinPipe return the underlying connection as WriteCloser, wrapped to prevent
+// StdinPipe returns the underlying connection as WriteCloser, wrapped to prevent
 // call to the Close function from the connection, a command execution in git
 // protocol can't be closed or killed
 func (c *command) StdinPipe() (io.WriteCloser, error) {
 	return ioutil.WriteNopCloser(c.conn), nil
 }
 
-// StdoutPipe return the underlying connection as Reader
+// StdoutPipe returns the underlying connection as Reader
 func (c *command) StdoutPipe() (io.Reader, error) {
 	return c.conn, nil
 }
diff --git a/plumbing/transport/internal/common/common.go b/plumbing/transport/internal/common/common.go
index fdb148f59..d0e9a2974 100644
--- a/plumbing/transport/internal/common/common.go
+++ b/plumbing/transport/internal/common/common.go
@@ -428,11 +428,6 @@ func isRepoNotFoundError(s string) bool {
 	return false
 }
 
-var (
-	nak = []byte("NAK")
-	eol = []byte("\n")
-)
-
 // uploadPack implements the git-upload-pack protocol.
 func uploadPack(w io.WriteCloser, r io.Reader, req *packp.UploadPackRequest) error {
 	// TODO support multi_ack mode
diff --git a/plumbing/transport/server/server.go b/plumbing/transport/server/server.go
index 8ab70fe70..11fa0c801 100644
--- a/plumbing/transport/server/server.go
+++ b/plumbing/transport/server/server.go
@@ -189,7 +189,7 @@ func (s *upSession) objectsToUpload(req *packp.UploadPackRequest) ([]plumbing.Ha
 }
 
 func (*upSession) setSupportedCapabilities(c *capability.List) error {
-	if err := c.Set(capability.Agent, capability.DefaultAgent); err != nil {
+	if err := c.Set(capability.Agent, capability.DefaultAgent()); err != nil {
 		return err
 	}
 
@@ -355,7 +355,7 @@ func (s *rpSession) reportStatus() *packp.ReportStatus {
 }
 
 func (*rpSession) setSupportedCapabilities(c *capability.List) error {
-	if err := c.Set(capability.Agent, capability.DefaultAgent); err != nil {
+	if err := c.Set(capability.Agent, capability.DefaultAgent()); err != nil {
 		return err
 	}
 
diff --git a/plumbing/transport/ssh/auth_method.go b/plumbing/transport/ssh/auth_method.go
index 351466954..9d3bcd359 100644
--- a/plumbing/transport/ssh/auth_method.go
+++ b/plumbing/transport/ssh/auth_method.go
@@ -10,10 +10,9 @@ import (
 
 	"github.com/go-git/go-git/v5/plumbing/transport"
 
-	"github.com/mitchellh/go-homedir"
+	"github.com/skeema/knownhosts"
 	sshagent "github.com/xanzy/ssh-agent"
 	"golang.org/x/crypto/ssh"
-	"golang.org/x/crypto/ssh/knownhosts"
 )
 
 const DefaultUsername = "git"
@@ -44,7 +43,6 @@ const (
 type KeyboardInteractive struct {
 	User      string
 	Challenge ssh.KeyboardInteractiveChallenge
-	HostKeyCallbackHelper
 }
 
 func (a *KeyboardInteractive) Name() string {
@@ -56,19 +54,18 @@ func (a *KeyboardInteractive) String() string {
 }
 
 func (a *KeyboardInteractive) ClientConfig() (*ssh.ClientConfig, error) {
-	return a.SetHostKeyCallback(&ssh.ClientConfig{
+	return &ssh.ClientConfig{
 		User: a.User,
 		Auth: []ssh.AuthMethod{
 			a.Challenge,
 		},
-	})
+	}, nil
 }
 
 // Password implements AuthMethod by using the given password.
 type Password struct {
 	User     string
 	Password string
-	HostKeyCallbackHelper
 }
 
 func (a *Password) Name() string {
@@ -80,10 +77,10 @@ func (a *Password) String() string {
 }
 
 func (a *Password) ClientConfig() (*ssh.ClientConfig, error) {
-	return a.SetHostKeyCallback(&ssh.ClientConfig{
+	return &ssh.ClientConfig{
 		User: a.User,
 		Auth: []ssh.AuthMethod{ssh.Password(a.Password)},
-	})
+	}, nil
 }
 
 // PasswordCallback implements AuthMethod by using a callback
@@ -91,7 +88,6 @@ func (a *Password) ClientConfig() (*ssh.ClientConfig, error) {
 type PasswordCallback struct {
 	User     string
 	Callback func() (pass string, err error)
-	HostKeyCallbackHelper
 }
 
 func (a *PasswordCallback) Name() string {
@@ -103,17 +99,16 @@ func (a *PasswordCallback) String() string {
 }
 
 func (a *PasswordCallback) ClientConfig() (*ssh.ClientConfig, error) {
-	return a.SetHostKeyCallback(&ssh.ClientConfig{
+	return &ssh.ClientConfig{
 		User: a.User,
 		Auth: []ssh.AuthMethod{ssh.PasswordCallback(a.Callback)},
-	})
+	}, nil
 }
 
 // PublicKeys implements AuthMethod by using the given key pairs.
 type PublicKeys struct {
 	User   string
 	Signer ssh.Signer
-	HostKeyCallbackHelper
 }
 
 // NewPublicKeys returns a PublicKeys from a PEM encoded private key. An
@@ -152,10 +147,10 @@ func (a *PublicKeys) String() string {
 }
 
 func (a *PublicKeys) ClientConfig() (*ssh.ClientConfig, error) {
-	return a.SetHostKeyCallback(&ssh.ClientConfig{
+	return &ssh.ClientConfig{
 		User: a.User,
 		Auth: []ssh.AuthMethod{ssh.PublicKeys(a.Signer)},
-	})
+	}, nil
 }
 
 func username() (string, error) {
@@ -178,7 +173,6 @@ func username() (string, error) {
 type PublicKeysCallback struct {
 	User     string
 	Callback func() (signers []ssh.Signer, err error)
-	HostKeyCallbackHelper
 }
 
 // NewSSHAgentAuth returns a PublicKeysCallback based on a SSH agent, it opens
@@ -213,10 +207,10 @@ func (a *PublicKeysCallback) String() string {
 }
 
 func (a *PublicKeysCallback) ClientConfig() (*ssh.ClientConfig, error) {
-	return a.SetHostKeyCallback(&ssh.ClientConfig{
+	return &ssh.ClientConfig{
 		User: a.User,
 		Auth: []ssh.AuthMethod{ssh.PublicKeysCallback(a.Callback)},
-	})
+	}, nil
 }
 
 // NewKnownHostsCallback returns ssh.HostKeyCallback based on a file based on a
@@ -224,12 +218,19 @@ func (a *PublicKeysCallback) ClientConfig() (*ssh.ClientConfig, error) {
 //
 // If list of files is empty, then it will be read from the SSH_KNOWN_HOSTS
 // environment variable, example:
-//   /home/foo/custom_known_hosts_file:/etc/custom_known/hosts_file
+//
+//	/home/foo/custom_known_hosts_file:/etc/custom_known/hosts_file
 //
 // If SSH_KNOWN_HOSTS is not set the following file locations will be used:
-//   ~/.ssh/known_hosts
-//   /etc/ssh/ssh_known_hosts
+//
+//	~/.ssh/known_hosts
+//	/etc/ssh/ssh_known_hosts
 func NewKnownHostsCallback(files ...string) (ssh.HostKeyCallback, error) {
+	kh, err := newKnownHosts(files...)
+	return ssh.HostKeyCallback(kh), err
+}
+
+func newKnownHosts(files ...string) (knownhosts.HostKeyCallback, error) {
 	var err error
 
 	if len(files) == 0 {
@@ -251,7 +252,7 @@ func getDefaultKnownHostsFiles() ([]string, error) {
 		return files, nil
 	}
 
-	homeDirPath, err := homedir.Dir()
+	homeDirPath, err := os.UserHomeDir()
 	if err != nil {
 		return nil, err
 	}
@@ -285,6 +286,9 @@ func filterKnownHostsFiles(files ...string) ([]string, error) {
 
 // HostKeyCallbackHelper is a helper that provides common functionality to
 // configure HostKeyCallback into a ssh.ClientConfig.
+// Deprecated in favor of SetConfigHostKeyFields (see common.go) which provides
+// a mechanism for also setting ClientConfig.HostKeyAlgorithms for a specific
+// host.
 type HostKeyCallbackHelper struct {
 	// HostKeyCallback is the function type used for verifying server keys.
 	// If nil default callback will be create using NewKnownHostsCallback
diff --git a/plumbing/transport/ssh/common.go b/plumbing/transport/ssh/common.go
index 46e79134c..4b9ac0797 100644
--- a/plumbing/transport/ssh/common.go
+++ b/plumbing/transport/ssh/common.go
@@ -121,10 +121,15 @@ func (c *command) connect() error {
 	if err != nil {
 		return err
 	}
+	hostWithPort := c.getHostWithPort()
+	config, err = SetConfigHostKeyFields(config, hostWithPort)
+	if err != nil {
+		return err
+	}
 
 	overrideConfig(c.config, config)
 
-	c.client, err = dial("tcp", c.getHostWithPort(), config)
+	c.client, err = dial("tcp", hostWithPort, config)
 	if err != nil {
 		return err
 	}
@@ -162,6 +167,23 @@ func dial(network, addr string, config *ssh.ClientConfig) (*ssh.Client, error) {
 	return ssh.NewClient(c, chans, reqs), nil
 }
 
+// SetConfigHostKeyFields sets cfg.HostKeyCallback and cfg.HostKeyAlgorithms
+// based on OpenSSH known_hosts. cfg is modified in-place. hostWithPort must be
+// supplied, since the algorithms will be set based on the known host keys for
+// that specific host. Otherwise, golang.org/x/crypto/ssh can return an error
+// upon connecting to a host whose *first* key is not known, even though other
+// keys (of different types) are known and match properly.
+// For background see https://github.com/go-git/go-git/issues/411 as well as
+// https://github.com/golang/go/issues/29286 for root cause.
+func SetConfigHostKeyFields(cfg *ssh.ClientConfig, hostWithPort string) (*ssh.ClientConfig, error) {
+	kh, err := newKnownHosts()
+	if err == nil {
+		cfg.HostKeyCallback = kh.HostKeyCallback()
+		cfg.HostKeyAlgorithms = kh.HostKeyAlgorithms(hostWithPort)
+	}
+	return cfg, err
+}
+
 func (c *command) getHostWithPort() string {
 	if addr, found := c.doGetHostWithPortFromSSHConfig(); found {
 		return addr
diff --git a/plumbing/transport/ssh/common_test.go b/plumbing/transport/ssh/common_test.go
index e04a9c5dc..6d634d532 100644
--- a/plumbing/transport/ssh/common_test.go
+++ b/plumbing/transport/ssh/common_test.go
@@ -7,7 +7,6 @@ import (
 
 	"github.com/kevinburke/ssh_config"
 	"golang.org/x/crypto/ssh"
-	stdssh "golang.org/x/crypto/ssh"
 	. "gopkg.in/check.v1"
 )
 
@@ -99,7 +98,7 @@ func (s *SuiteCommon) TestIssue70(c *C) {
 	uploadPack.SetUpSuite(c)
 
 	config := &ssh.ClientConfig{
-		HostKeyCallback: stdssh.InsecureIgnoreHostKey(),
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
 	}
 	r := &runner{
 		config: config,
diff --git a/prune.go b/prune.go
index cc5907a14..8e35b994e 100644
--- a/prune.go
+++ b/prune.go
@@ -17,7 +17,7 @@ type PruneOptions struct {
 	Handler PruneHandler
 }
 
-var ErrLooseObjectsNotSupported = errors.New("Loose objects not supported")
+var ErrLooseObjectsNotSupported = errors.New("loose objects not supported")
 
 // DeleteObject deletes an object from a repository.
 // The type conveniently matches PruneHandler.
diff --git a/remote.go b/remote.go
index 4a06106c5..db78ae718 100644
--- a/remote.go
+++ b/remote.go
@@ -5,10 +5,12 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"strings"
 	"time"
 
 	"github.com/go-git/go-billy/v5/osfs"
 	"github.com/go-git/go-git/v5/config"
+	"github.com/go-git/go-git/v5/internal/url"
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/plumbing/cache"
 	"github.com/go-git/go-git/v5/plumbing/format/packfile"
@@ -103,7 +105,11 @@ func (r *Remote) PushContext(ctx context.Context, o *PushOptions) (err error) {
 		return fmt.Errorf("remote names don't match: %s != %s", o.RemoteName, r.c.Name)
 	}
 
-	s, err := newSendPackSession(r.c.URLs[0], o.Auth, o.InsecureSkipTLS, o.CABundle)
+	if o.RemoteURL == "" {
+		o.RemoteURL = r.c.URLs[0]
+	}
+
+	s, err := newSendPackSession(o.RemoteURL, o.Auth, o.InsecureSkipTLS, o.CABundle)
 	if err != nil {
 		return err
 	}
@@ -183,12 +189,12 @@ func (r *Remote) PushContext(ctx context.Context, o *PushOptions) (err error) {
 	var hashesToPush []plumbing.Hash
 	// Avoid the expensive revlist operation if we're only doing deletes.
 	if !allDelete {
-		if r.c.IsFirstURLLocal() {
+		if url.IsLocalEndpoint(o.RemoteURL) {
 			// If we're are pushing to a local repo, it might be much
 			// faster to use a local storage layer to get the commits
 			// to ignore, when calculating the object revlist.
 			localStorer := filesystem.NewStorage(
-				osfs.New(r.c.URLs[0]), cache.NewObjectLRUDefault())
+				osfs.New(o.RemoteURL), cache.NewObjectLRUDefault())
 			hashesToPush, err = revlist.ObjectsWithStorageForIgnores(
 				r.s, localStorer, objects, haves)
 		} else {
@@ -225,6 +231,74 @@ func (r *Remote) useRefDeltas(ar *packp.AdvRefs) bool {
 	return !ar.Capabilities.Supports(capability.OFSDelta)
 }
 
+func (r *Remote) addReachableTags(localRefs []*plumbing.Reference, remoteRefs storer.ReferenceStorer, req *packp.ReferenceUpdateRequest) error {
+	tags := make(map[plumbing.Reference]struct{})
+	// get a list of all tags locally
+	for _, ref := range localRefs {
+		if strings.HasPrefix(string(ref.Name()), "refs/tags") {
+			tags[*ref] = struct{}{}
+		}
+	}
+
+	remoteRefIter, err := remoteRefs.IterReferences()
+	if err != nil {
+		return err
+	}
+
+	// remove any that are already on the remote
+	if err := remoteRefIter.ForEach(func(reference *plumbing.Reference) error {
+		delete(tags, *reference)
+		return nil
+	}); err != nil {
+		return err
+	}
+
+	for tag := range tags {
+		tagObject, err := object.GetObject(r.s, tag.Hash())
+		var tagCommit *object.Commit
+		if err != nil {
+			return fmt.Errorf("get tag object: %w", err)
+		}
+
+		if tagObject.Type() != plumbing.TagObject {
+			continue
+		}
+
+		annotatedTag, ok := tagObject.(*object.Tag)
+		if !ok {
+			return errors.New("could not get annotated tag object")
+		}
+
+		tagCommit, err = object.GetCommit(r.s, annotatedTag.Target)
+		if err != nil {
+			return fmt.Errorf("get annotated tag commit: %w", err)
+		}
+
+		// only include tags that are reachable from one of the refs
+		// already being pushed
+		for _, cmd := range req.Commands {
+			if tag.Name() == cmd.Name {
+				continue
+			}
+
+			if strings.HasPrefix(cmd.Name.String(), "refs/tags") {
+				continue
+			}
+
+			c, err := object.GetCommit(r.s, cmd.New)
+			if err != nil {
+				return fmt.Errorf("get commit %v: %w", cmd.Name, err)
+			}
+
+			if isAncestor, err := tagCommit.IsAncestor(c); err == nil && isAncestor {
+				req.Commands = append(req.Commands, &packp.Command{Name: tag.Name(), New: tag.Hash()})
+			}
+		}
+	}
+
+	return nil
+}
+
 func (r *Remote) newReferenceUpdateRequest(
 	o *PushOptions,
 	localRefs []*plumbing.Reference,
@@ -242,10 +316,28 @@ func (r *Remote) newReferenceUpdateRequest(
 		}
 	}
 
-	if err := r.addReferencesToUpdate(o.RefSpecs, localRefs, remoteRefs, req, o.Prune); err != nil {
+	if ar.Capabilities.Supports(capability.PushOptions) {
+		_ = req.Capabilities.Set(capability.PushOptions)
+		for k, v := range o.Options {
+			req.Options = append(req.Options, &packp.Option{Key: k, Value: v})
+		}
+	}
+
+	if o.Atomic && ar.Capabilities.Supports(capability.Atomic) {
+		_ = req.Capabilities.Set(capability.Atomic)
+	}
+
+	if err := r.addReferencesToUpdate(o.RefSpecs, localRefs, remoteRefs, req, o.Prune, o.ForceWithLease); err != nil {
+
 		return nil, err
 	}
 
+	if o.FollowTags {
+		if err := r.addReachableTags(localRefs, remoteRefs, req); err != nil {
+			return nil, err
+		}
+	}
+
 	return req, nil
 }
 
@@ -314,7 +406,11 @@ func (r *Remote) fetch(ctx context.Context, o *FetchOptions) (sto storer.Referen
 		o.RefSpecs = r.c.Fetch
 	}
 
-	s, err := newUploadPackSession(r.c.URLs[0], o.Auth, o.InsecureSkipTLS, o.CABundle)
+	if o.RemoteURL == "" {
+		o.RemoteURL = r.c.URLs[0]
+	}
+
+	s, err := newUploadPackSession(o.RemoteURL, o.Auth, o.InsecureSkipTLS, o.CABundle)
 	if err != nil {
 		return nil, err
 	}
@@ -474,6 +570,7 @@ func (r *Remote) addReferencesToUpdate(
 	remoteRefs storer.ReferenceStorer,
 	req *packp.ReferenceUpdateRequest,
 	prune bool,
+	forceWithLease *ForceWithLease,
 ) error {
 	// This references dictionary will be used to search references by name.
 	refsDict := make(map[string]*plumbing.Reference)
@@ -487,7 +584,7 @@ func (r *Remote) addReferencesToUpdate(
 				return err
 			}
 		} else {
-			err := r.addOrUpdateReferences(rs, localRefs, refsDict, remoteRefs, req)
+			err := r.addOrUpdateReferences(rs, localRefs, refsDict, remoteRefs, req, forceWithLease)
 			if err != nil {
 				return err
 			}
@@ -509,20 +606,25 @@ func (r *Remote) addOrUpdateReferences(
 	refsDict map[string]*plumbing.Reference,
 	remoteRefs storer.ReferenceStorer,
 	req *packp.ReferenceUpdateRequest,
+	forceWithLease *ForceWithLease,
 ) error {
 	// If it is not a wilcard refspec we can directly search for the reference
 	// in the references dictionary.
 	if !rs.IsWildcard() {
 		ref, ok := refsDict[rs.Src()]
 		if !ok {
+			commit, err := object.GetCommit(r.s, plumbing.NewHash(rs.Src()))
+			if err == nil {
+				return r.addCommit(rs, remoteRefs, commit.Hash, req)
+			}
 			return nil
 		}
 
-		return r.addReferenceIfRefSpecMatches(rs, remoteRefs, ref, req)
+		return r.addReferenceIfRefSpecMatches(rs, remoteRefs, ref, req, forceWithLease)
 	}
 
 	for _, ref := range localRefs {
-		err := r.addReferenceIfRefSpecMatches(rs, remoteRefs, ref, req)
+		err := r.addReferenceIfRefSpecMatches(rs, remoteRefs, ref, req, forceWithLease)
 		if err != nil {
 			return err
 		}
@@ -569,9 +671,46 @@ func (r *Remote) deleteReferences(rs config.RefSpec,
 	})
 }
 
+func (r *Remote) addCommit(rs config.RefSpec,
+	remoteRefs storer.ReferenceStorer, localCommit plumbing.Hash,
+	req *packp.ReferenceUpdateRequest) error {
+
+	if rs.IsWildcard() {
+		return errors.New("can't use wildcard together with hash refspecs")
+	}
+
+	cmd := &packp.Command{
+		Name: rs.Dst(""),
+		Old:  plumbing.ZeroHash,
+		New:  localCommit,
+	}
+	remoteRef, err := remoteRefs.Reference(cmd.Name)
+	if err == nil {
+		if remoteRef.Type() != plumbing.HashReference {
+			//TODO: check actual git behavior here
+			return nil
+		}
+
+		cmd.Old = remoteRef.Hash()
+	} else if err != plumbing.ErrReferenceNotFound {
+		return err
+	}
+	if cmd.Old == cmd.New {
+		return nil
+	}
+	if !rs.IsForceUpdate() {
+		if err := checkFastForwardUpdate(r.s, remoteRefs, cmd); err != nil {
+			return err
+		}
+	}
+
+	req.Commands = append(req.Commands, cmd)
+	return nil
+}
+
 func (r *Remote) addReferenceIfRefSpecMatches(rs config.RefSpec,
 	remoteRefs storer.ReferenceStorer, localRef *plumbing.Reference,
-	req *packp.ReferenceUpdateRequest) error {
+	req *packp.ReferenceUpdateRequest, forceWithLease *ForceWithLease) error {
 
 	if localRef.Type() != plumbing.HashReference {
 		return nil
@@ -603,7 +742,11 @@ func (r *Remote) addReferenceIfRefSpecMatches(rs config.RefSpec,
 		return nil
 	}
 
-	if !rs.IsForceUpdate() {
+	if forceWithLease != nil {
+		if err = r.checkForceWithLease(localRef, cmd, forceWithLease); err != nil {
+			return err
+		}
+	} else if !rs.IsForceUpdate() {
 		if err := checkFastForwardUpdate(r.s, remoteRefs, cmd); err != nil {
 			return err
 		}
@@ -613,6 +756,31 @@ func (r *Remote) addReferenceIfRefSpecMatches(rs config.RefSpec,
 	return nil
 }
 
+func (r *Remote) checkForceWithLease(localRef *plumbing.Reference, cmd *packp.Command, forceWithLease *ForceWithLease) error {
+	remotePrefix := fmt.Sprintf("refs/remotes/%s/", r.Config().Name)
+
+	ref, err := storer.ResolveReference(
+		r.s,
+		plumbing.ReferenceName(remotePrefix+strings.Replace(localRef.Name().String(), "refs/heads/", "", -1)))
+	if err != nil {
+		return err
+	}
+
+	if forceWithLease.RefName.String() == "" || (forceWithLease.RefName == cmd.Name) {
+		expectedOID := ref.Hash()
+
+		if !forceWithLease.Hash.IsZero() {
+			expectedOID = forceWithLease.Hash
+		}
+
+		if cmd.Old != expectedOID {
+			return fmt.Errorf("non-fast-forward update: %s", cmd.Name.String())
+		}
+	}
+
+	return nil
+}
+
 func (r *Remote) references() ([]*plumbing.Reference, error) {
 	var localRefs []*plumbing.Reference
 
diff --git a/remote_test.go b/remote_test.go
index 1efc9da70..751c89a1b 100644
--- a/remote_test.go
+++ b/remote_test.go
@@ -5,12 +5,16 @@ import (
 	"context"
 	"errors"
 	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
 	"runtime"
 	"time"
 
 	"github.com/go-git/go-git/v5/config"
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/plumbing/cache"
+	"github.com/go-git/go-git/v5/plumbing/object"
 	"github.com/go-git/go-git/v5/plumbing/protocol/packp"
 	"github.com/go-git/go-git/v5/plumbing/protocol/packp/capability"
 	"github.com/go-git/go-git/v5/plumbing/storer"
@@ -46,6 +50,12 @@ func (s *RemoteSuite) TestFetchInvalidSchemaEndpoint(c *C) {
 	c.Assert(err, ErrorMatches, ".*unsupported scheme.*")
 }
 
+func (s *RemoteSuite) TestFetchOverriddenEndpoint(c *C) {
+	r := NewRemote(nil, &config.RemoteConfig{Name: "foo", URLs: []string{"http://perfectly-valid-url.example.com"}})
+	err := r.Fetch(&FetchOptions{RemoteURL: "http://\\"})
+	c.Assert(err, ErrorMatches, ".*invalid character.*")
+}
+
 func (s *RemoteSuite) TestFetchInvalidFetchOptions(c *C) {
 	r := NewRemote(nil, &config.RemoteConfig{Name: "foo", URLs: []string{"qux://foo"}})
 	invalid := config.RefSpec("^*$ñ")
@@ -525,10 +535,22 @@ func (s *RemoteSuite) TestPushContext(c *C) {
 	})
 	c.Assert(err, IsNil)
 
-	// let the goroutine from pushHashes finish and check that the number of
-	// goroutines is the same as before
-	time.Sleep(100 * time.Millisecond)
-	c.Assert(runtime.NumGoroutine(), Equals, numGoroutines)
+	eventually(c, func() bool {
+		return runtime.NumGoroutine() <= numGoroutines
+	})
+}
+
+func eventually(c *C, condition func() bool) {
+	select {
+	case <-time.After(5 * time.Second):
+	default:
+		if condition() {
+			break
+		}
+		time.Sleep(100 * time.Millisecond)
+	}
+
+	c.Assert(condition(), Equals, true)
 }
 
 func (s *RemoteSuite) TestPushContextCanceled(c *C) {
@@ -556,10 +578,9 @@ func (s *RemoteSuite) TestPushContextCanceled(c *C) {
 	})
 	c.Assert(err, Equals, context.Canceled)
 
-	// let the goroutine from pushHashes finish and check that the number of
-	// goroutines is the same as before
-	time.Sleep(100 * time.Millisecond)
-	c.Assert(runtime.NumGoroutine(), Equals, numGoroutines)
+	eventually(c, func() bool {
+		return runtime.NumGoroutine() <= numGoroutines
+	})
 }
 
 func (s *RemoteSuite) TestPushTags(c *C) {
@@ -591,6 +612,66 @@ func (s *RemoteSuite) TestPushTags(c *C) {
 	})
 }
 
+func (s *RemoteSuite) TestPushFollowTags(c *C) {
+	url, clean := s.TemporalDir()
+	defer clean()
+
+	server, err := PlainInit(url, true)
+	c.Assert(err, IsNil)
+
+	fs := fixtures.ByURL("https://github.com/git-fixtures/basic.git").One().DotGit()
+	sto := filesystem.NewStorage(fs, cache.NewObjectLRUDefault())
+
+	r := NewRemote(sto, &config.RemoteConfig{
+		Name: DefaultRemoteName,
+		URLs: []string{url},
+	})
+
+	localRepo := newRepository(sto, fs)
+	tipTag, err := localRepo.CreateTag(
+		"tip",
+		plumbing.NewHash("e8d3ffab552895c19b9fcf7aa264d277cde33881"),
+		&CreateTagOptions{
+			Message: "an annotated tag",
+		},
+	)
+	c.Assert(err, IsNil)
+
+	initialTag, err := localRepo.CreateTag(
+		"initial-commit",
+		plumbing.NewHash("b029517f6300c2da0f4b651b8642506cd6aaf45d"),
+		&CreateTagOptions{
+			Message: "a tag for the initial commit",
+		},
+	)
+	c.Assert(err, IsNil)
+
+	_, err = localRepo.CreateTag(
+		"master-tag",
+		plumbing.NewHash("6ecf0ef2c2dffb796033e5a02219af86ec6584e5"),
+		&CreateTagOptions{
+			Message: "a tag with a commit not reachable from branch",
+		},
+	)
+	c.Assert(err, IsNil)
+
+	err = r.Push(&PushOptions{
+		RefSpecs:   []config.RefSpec{"+refs/heads/branch:refs/heads/branch"},
+		FollowTags: true,
+	})
+	c.Assert(err, IsNil)
+
+	AssertReferences(c, server, map[string]string{
+		"refs/heads/branch":        "e8d3ffab552895c19b9fcf7aa264d277cde33881",
+		"refs/tags/tip":            tipTag.Hash().String(),
+		"refs/tags/initial-commit": initialTag.Hash().String(),
+	})
+
+	AssertReferencesMissing(c, server, []string{
+		"refs/tags/master-tag",
+	})
+}
+
 func (s *RemoteSuite) TestPushNoErrAlreadyUpToDate(c *C) {
 	fs := fixtures.Basic().One().DotGit()
 	sto := filesystem.NewStorage(fs, cache.NewObjectLRUDefault())
@@ -746,6 +827,133 @@ func (s *RemoteSuite) TestPushForceWithOption(c *C) {
 	c.Assert(newRef, Not(DeepEquals), oldRef)
 }
 
+func (s *RemoteSuite) TestPushForceWithLease_success(c *C) {
+	testCases := []struct {
+		desc           string
+		forceWithLease ForceWithLease
+	}{
+		{
+			desc:           "no arguments",
+			forceWithLease: ForceWithLease{},
+		},
+		{
+			desc: "ref name",
+			forceWithLease: ForceWithLease{
+				RefName: plumbing.ReferenceName("refs/heads/branch"),
+			},
+		},
+		{
+			desc: "ref name and sha",
+			forceWithLease: ForceWithLease{
+				RefName: plumbing.ReferenceName("refs/heads/branch"),
+				Hash:    plumbing.NewHash("e8d3ffab552895c19b9fcf7aa264d277cde33881"),
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		c.Log("Executing test cases:", tc.desc)
+
+		f := fixtures.Basic().One()
+		sto := filesystem.NewStorage(f.DotGit(), cache.NewObjectLRUDefault())
+		dstFs := f.DotGit()
+		dstSto := filesystem.NewStorage(dstFs, cache.NewObjectLRUDefault())
+
+		newCommit := plumbing.NewHashReference(
+			"refs/heads/branch", plumbing.NewHash("35e85108805c84807bc66a02d91535e1e24b38b9"),
+		)
+		c.Assert(sto.SetReference(newCommit), IsNil)
+
+		ref, err := sto.Reference("refs/heads/branch")
+		c.Log(ref.String())
+
+		url := dstFs.Root()
+		r := NewRemote(sto, &config.RemoteConfig{
+			Name: DefaultRemoteName,
+			URLs: []string{url},
+		})
+
+		oldRef, err := dstSto.Reference("refs/heads/branch")
+		c.Assert(err, IsNil)
+		c.Assert(oldRef, NotNil)
+
+		c.Assert(r.Push(&PushOptions{
+			RefSpecs:       []config.RefSpec{"refs/heads/branch:refs/heads/branch"},
+			ForceWithLease: &ForceWithLease{},
+		}), IsNil)
+
+		newRef, err := dstSto.Reference("refs/heads/branch")
+		c.Assert(err, IsNil)
+		c.Assert(newRef, DeepEquals, newCommit)
+	}
+}
+
+func (s *RemoteSuite) TestPushForceWithLease_failure(c *C) {
+	testCases := []struct {
+		desc           string
+		forceWithLease ForceWithLease
+	}{
+		{
+			desc:           "no arguments",
+			forceWithLease: ForceWithLease{},
+		},
+		{
+			desc: "ref name",
+			forceWithLease: ForceWithLease{
+				RefName: plumbing.ReferenceName("refs/heads/branch"),
+			},
+		},
+		{
+			desc: "ref name and sha",
+			forceWithLease: ForceWithLease{
+				RefName: plumbing.ReferenceName("refs/heads/branch"),
+				Hash:    plumbing.NewHash("152175bf7e5580299fa1f0ba41ef6474cc043b70"),
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		c.Log("Executing test cases:", tc.desc)
+
+		f := fixtures.Basic().One()
+		sto := filesystem.NewStorage(f.DotGit(), cache.NewObjectLRUDefault())
+		c.Assert(sto.SetReference(
+			plumbing.NewHashReference(
+				"refs/heads/branch", plumbing.NewHash("35e85108805c84807bc66a02d91535e1e24b38b9"),
+			),
+		), IsNil)
+
+		dstFs := f.DotGit()
+		dstSto := filesystem.NewStorage(dstFs, cache.NewObjectLRUDefault())
+		c.Assert(dstSto.SetReference(
+			plumbing.NewHashReference(
+				"refs/heads/branch", plumbing.NewHash("ad7897c0fb8e7d9a9ba41fa66072cf06095a6cfc"),
+			),
+		), IsNil)
+
+		url := dstFs.Root()
+		r := NewRemote(sto, &config.RemoteConfig{
+			Name: DefaultRemoteName,
+			URLs: []string{url},
+		})
+
+		oldRef, err := dstSto.Reference("refs/heads/branch")
+		c.Assert(err, IsNil)
+		c.Assert(oldRef, NotNil)
+
+		err = r.Push(&PushOptions{
+			RefSpecs:       []config.RefSpec{"refs/heads/branch:refs/heads/branch"},
+			ForceWithLease: &ForceWithLease{},
+		})
+
+		c.Assert(err, DeepEquals, errors.New("non-fast-forward update: refs/heads/branch"))
+
+		newRef, err := dstSto.Reference("refs/heads/branch")
+		c.Assert(err, IsNil)
+		c.Assert(newRef, Not(DeepEquals), plumbing.NewHash("35e85108805c84807bc66a02d91535e1e24b38b9"))
+	}
+}
+
 func (s *RemoteSuite) TestPushPrune(c *C) {
 	fs := fixtures.Basic().One().DotGit()
 
@@ -805,7 +1013,7 @@ func (s *RemoteSuite) TestPushPrune(c *C) {
 		"refs/remotes/origin/master": ref.Hash().String(),
 	})
 
-	ref, err = server.Reference(plumbing.ReferenceName("refs/tags/v1.0.0"), true)
+	_, err = server.Reference(plumbing.ReferenceName("refs/tags/v1.0.0"), true)
 	c.Assert(err, Equals, plumbing.ErrReferenceNotFound)
 }
 
@@ -903,6 +1111,12 @@ func (s *RemoteSuite) TestPushNonExistentEndpoint(c *C) {
 	c.Assert(err, NotNil)
 }
 
+func (s *RemoteSuite) TestPushOverriddenEndpoint(c *C) {
+	r := NewRemote(nil, &config.RemoteConfig{Name: "origin", URLs: []string{"http://perfectly-valid-url.example.com"}})
+	err := r.Push(&PushOptions{RemoteURL: "http://\\"})
+	c.Assert(err, ErrorMatches, ".*invalid character.*")
+}
+
 func (s *RemoteSuite) TestPushInvalidSchemaEndpoint(c *C) {
 	r := NewRemote(nil, &config.RemoteConfig{Name: "origin", URLs: []string{"qux://foo"}})
 	err := r.Push(&PushOptions{})
@@ -1134,3 +1348,91 @@ func (s *RemoteSuite) TestPushRequireRemoteRefs(c *C) {
 	c.Assert(err, IsNil)
 	c.Assert(newRef, Not(DeepEquals), oldRef)
 }
+
+func (s *RemoteSuite) TestCanPushShasToReference(c *C) {
+	d, err := ioutil.TempDir("", "TestCanPushShasToReference")
+	c.Assert(err, IsNil)
+	if err != nil {
+		return
+	}
+	defer os.RemoveAll(d)
+
+	// remote currently forces a plain path for path based remotes inside the PushContext function.
+	// This makes it impossible, in the current state to use memfs.
+	// For the sake of readability, use the same osFS everywhere and use plain git repositories on temporary files
+	remote, err := PlainInit(filepath.Join(d, "remote"), true)
+	c.Assert(err, IsNil)
+	c.Assert(remote, NotNil)
+
+	repo, err := PlainInit(filepath.Join(d, "repo"), false)
+	c.Assert(err, IsNil)
+	c.Assert(repo, NotNil)
+
+	fd, err := os.Create(filepath.Join(d, "repo", "README.md"))
+	c.Assert(err, IsNil)
+	if err != nil {
+		return
+	}
+	_, err = fd.WriteString("# test repo")
+	c.Assert(err, IsNil)
+	if err != nil {
+		return
+	}
+	err = fd.Close()
+	c.Assert(err, IsNil)
+	if err != nil {
+		return
+	}
+
+	wt, err := repo.Worktree()
+	c.Assert(err, IsNil)
+	if err != nil {
+		return
+	}
+
+	wt.Add("README.md")
+	sha, err := wt.Commit("test commit", &CommitOptions{
+		Author: &object.Signature{
+			Name:  "test",
+			Email: "test@example.com",
+			When:  time.Now(),
+		},
+		Committer: &object.Signature{
+			Name:  "test",
+			Email: "test@example.com",
+			When:  time.Now(),
+		},
+	})
+	c.Assert(err, IsNil)
+	if err != nil {
+		return
+	}
+
+	gitremote, err := repo.CreateRemote(&config.RemoteConfig{
+		Name: "local",
+		URLs: []string{filepath.Join(d, "remote")},
+	})
+	c.Assert(err, IsNil)
+	if err != nil {
+		return
+	}
+
+	err = gitremote.Push(&PushOptions{
+		RemoteName: "local",
+		RefSpecs: []config.RefSpec{
+			// TODO: check with short hashes that this is still respected
+			config.RefSpec(sha.String() + ":refs/heads/branch"),
+		},
+	})
+	c.Assert(err, IsNil)
+	if err != nil {
+		return
+	}
+
+	ref, err := remote.Reference(plumbing.ReferenceName("refs/heads/branch"), false)
+	c.Assert(err, IsNil)
+	if err != nil {
+		return
+	}
+	c.Assert(ref.Hash().String(), Equals, sha.String())
+}
diff --git a/repository.go b/repository.go
index d3fbf9759..7292df627 100644
--- a/repository.go
+++ b/repository.go
@@ -56,7 +56,7 @@ var (
 	ErrWorktreeNotProvided       = errors.New("worktree should be provided")
 	ErrIsBareRepository          = errors.New("worktree not available in a bare repository")
 	ErrUnableToResolveCommit     = errors.New("unable to resolve commit")
-	ErrPackedObjectsNotSupported = errors.New("Packed objects not supported")
+	ErrPackedObjectsNotSupported = errors.New("packed objects not supported")
 )
 
 // Repository represents a git repository
@@ -280,6 +280,9 @@ func dotGitToOSFilesystems(path string, detect bool) (dot, wt billy.Filesystem,
 
 		pathinfo, err := fs.Stat("/")
 		if !os.IsNotExist(err) {
+			if pathinfo == nil {
+				return nil, nil, err
+			}
 			if !pathinfo.IsDir() && detect {
 				fs = osfs.New(filepath.Dir(path))
 			}
@@ -1547,7 +1550,7 @@ func (r *Repository) ResolveRevision(rev plumbing.Revision) (*plumbing.Hash, err
 			}
 
 			if c == nil {
-				return &plumbing.ZeroHash, fmt.Errorf(`No commit message match regexp : "%s"`, re.String())
+				return &plumbing.ZeroHash, fmt.Errorf("no commit message match regexp: %q", re.String())
 			}
 
 			commit = c
diff --git a/repository_test.go b/repository_test.go
index 2bc5c902c..7a9db151d 100644
--- a/repository_test.go
+++ b/repository_test.go
@@ -210,6 +210,37 @@ func (s *RepositorySuite) TestCloneWithTags(c *C) {
 	c.Assert(count, Equals, 3)
 }
 
+func (s *RepositorySuite) TestCloneSparse(c *C) {
+	fs := memfs.New()
+	r, err := Clone(memory.NewStorage(), fs, &CloneOptions{
+		URL: s.GetBasicLocalRepositoryURL(),
+	})
+	c.Assert(err, IsNil)
+
+	w, err := r.Worktree()
+	c.Assert(err, IsNil)
+
+	sparseCheckoutDirectories := []string{"go", "json", "php"}
+	c.Assert(w.Checkout(&CheckoutOptions{
+		Branch:                    "refs/heads/master",
+		SparseCheckoutDirectories: sparseCheckoutDirectories,
+	}), IsNil)
+
+	fis, err := fs.ReadDir(".")
+	c.Assert(err, IsNil)
+	for _, fi := range fis {
+		c.Assert(fi.IsDir(), Equals, true)
+		var oneOfSparseCheckoutDirs bool
+
+		for _, sparseCheckoutDirectory := range sparseCheckoutDirectories {
+			if strings.HasPrefix(fi.Name(), sparseCheckoutDirectory) {
+				oneOfSparseCheckoutDirs = true
+			}
+		}
+		c.Assert(oneOfSparseCheckoutDirs, Equals, true)
+	}
+}
+
 func (s *RepositorySuite) TestCreateRemoteAndRemote(c *C) {
 	r, _ := Init(memory.NewStorage(), nil)
 	remote, err := r.CreateRemote(&config.RemoteConfig{
@@ -2756,7 +2787,7 @@ func (s *RepositorySuite) TestResolveRevisionWithErrors(c *C) {
 	datas := map[string]string{
 		"efs/heads/master~": "reference not found",
 		"HEAD^3":            `Revision invalid : "3" found must be 0, 1 or 2 after "^"`,
-		"HEAD^{/whatever}":  `No commit message match regexp : "whatever"`,
+		"HEAD^{/whatever}":  `no commit message match regexp: "whatever"`,
 		"4e1243bd22c66e76c2ba9eddc1f91394e57f9f83": "reference not found",
 	}
 
@@ -2917,6 +2948,11 @@ func (s *RepositorySuite) TestBrokenMultipleShallowFetch(c *C) {
 	c.Assert(err, IsNil)
 }
 
+func (s *RepositorySuite) TestDotGitToOSFilesystemsInvalidPath(c *C) {
+	_, _, err := dotGitToOSFilesystems("\000", false)
+	c.Assert(err, NotNil)
+}
+
 func BenchmarkObjects(b *testing.B) {
 	defer fixtures.Clean()
 
diff --git a/storage/filesystem/dotgit/dotgit_test.go b/storage/filesystem/dotgit/dotgit_test.go
index 4c2ae941c..a8f0eb754 100644
--- a/storage/filesystem/dotgit/dotgit_test.go
+++ b/storage/filesystem/dotgit/dotgit_test.go
@@ -3,6 +3,7 @@ package dotgit
 import (
 	"bufio"
 	"encoding/hex"
+	"io"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -510,13 +511,13 @@ func (s *SuiteDotGit) TestObjectPackWithKeepDescriptors(c *C) {
 	c.Assert(filepath.Ext(pack.Name()), Equals, ".pack")
 
 	// Move to an specific offset
-	pack.Seek(42, os.SEEK_SET)
+	pack.Seek(42, io.SeekStart)
 
 	pack2, err := dir.ObjectPack(plumbing.NewHash(f.PackfileHash))
 	c.Assert(err, IsNil)
 
 	// If the file is the same the offset should be the same
-	offset, err := pack2.Seek(0, os.SEEK_CUR)
+	offset, err := pack2.Seek(0, io.SeekCurrent)
 	c.Assert(err, IsNil)
 	c.Assert(offset, Equals, int64(42))
 
@@ -527,7 +528,7 @@ func (s *SuiteDotGit) TestObjectPackWithKeepDescriptors(c *C) {
 	c.Assert(err, IsNil)
 
 	// If the file is opened again its offset should be 0
-	offset, err = pack2.Seek(0, os.SEEK_CUR)
+	offset, err = pack2.Seek(0, io.SeekCurrent)
 	c.Assert(err, IsNil)
 	c.Assert(offset, Equals, int64(0))
 
@@ -653,7 +654,7 @@ func (s *SuiteDotGit) TestObject(c *C) {
 	fs.MkdirAll(incomingDirPath, os.FileMode(0755))
 	fs.Create(incomingFilePath)
 
-	file, err = dir.Object(plumbing.NewHash(incomingHash))
+	_, err = dir.Object(plumbing.NewHash(incomingHash))
 	c.Assert(err, IsNil)
 }
 
diff --git a/storage/filesystem/dotgit/reader.go b/storage/filesystem/dotgit/reader.go
new file mode 100644
index 000000000..975f92ac6
--- /dev/null
+++ b/storage/filesystem/dotgit/reader.go
@@ -0,0 +1,79 @@
+package dotgit
+
+import (
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/go-git/go-git/v5/plumbing"
+	"github.com/go-git/go-git/v5/plumbing/format/objfile"
+	"github.com/go-git/go-git/v5/utils/ioutil"
+)
+
+var _ (plumbing.EncodedObject) = &EncodedObject{}
+
+type EncodedObject struct {
+	dir *DotGit
+	h   plumbing.Hash
+	t   plumbing.ObjectType
+	sz  int64
+}
+
+func (e *EncodedObject) Hash() plumbing.Hash {
+	return e.h
+}
+
+func (e *EncodedObject) Reader() (io.ReadCloser, error) {
+	f, err := e.dir.Object(e.h)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, plumbing.ErrObjectNotFound
+		}
+
+		return nil, err
+	}
+	r, err := objfile.NewReader(f)
+	if err != nil {
+		return nil, err
+	}
+
+	t, size, err := r.Header()
+	if err != nil {
+		_ = r.Close()
+		return nil, err
+	}
+	if t != e.t {
+		_ = r.Close()
+		return nil, objfile.ErrHeader
+	}
+	if size != e.sz {
+		_ = r.Close()
+		return nil, objfile.ErrHeader
+	}
+	return ioutil.NewReadCloserWithCloser(r, f.Close), nil
+}
+
+func (e *EncodedObject) SetType(plumbing.ObjectType) {}
+
+func (e *EncodedObject) Type() plumbing.ObjectType {
+	return e.t
+}
+
+func (e *EncodedObject) Size() int64 {
+	return e.sz
+}
+
+func (e *EncodedObject) SetSize(int64) {}
+
+func (e *EncodedObject) Writer() (io.WriteCloser, error) {
+	return nil, fmt.Errorf("not supported")
+}
+
+func NewEncodedObject(dir *DotGit, h plumbing.Hash, t plumbing.ObjectType, size int64) *EncodedObject {
+	return &EncodedObject{
+		dir: dir,
+		h:   h,
+		t:   t,
+		sz:  size,
+	}
+}
diff --git a/storage/filesystem/object.go b/storage/filesystem/object.go
index 0c25dad61..21667fa5a 100644
--- a/storage/filesystem/object.go
+++ b/storage/filesystem/object.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"io"
 	"os"
+	"sync"
 	"time"
 
 	"github.com/go-git/go-git/v5/plumbing"
@@ -204,9 +205,9 @@ func (s *ObjectStorage) packfile(idx idxfile.Index, pack plumbing.Hash) (*packfi
 
 	var p *packfile.Packfile
 	if s.objectCache != nil {
-		p = packfile.NewPackfileWithCache(idx, s.dir.Fs(), f, s.objectCache)
+		p = packfile.NewPackfileWithCache(idx, s.dir.Fs(), f, s.objectCache, s.options.LargeObjectThreshold)
 	} else {
-		p = packfile.NewPackfile(idx, s.dir.Fs(), f)
+		p = packfile.NewPackfile(idx, s.dir.Fs(), f, s.options.LargeObjectThreshold)
 	}
 
 	return p, s.storePackfileInCache(pack, p)
@@ -389,7 +390,6 @@ func (s *ObjectStorage) getFromUnpacked(h plumbing.Hash) (obj plumbing.EncodedOb
 		return cacheObj, nil
 	}
 
-	obj = s.NewEncodedObject()
 	r, err := objfile.NewReader(f)
 	if err != nil {
 		return nil, err
@@ -402,6 +402,13 @@ func (s *ObjectStorage) getFromUnpacked(h plumbing.Hash) (obj plumbing.EncodedOb
 		return nil, err
 	}
 
+	if s.options.LargeObjectThreshold > 0 && size > s.options.LargeObjectThreshold {
+		obj = dotgit.NewEncodedObject(s.dir, h, t, size)
+		return obj, nil
+	}
+
+	obj = s.NewEncodedObject()
+
 	obj.SetType(t)
 	obj.SetSize(size)
 	w, err := obj.Writer()
@@ -413,10 +420,21 @@ func (s *ObjectStorage) getFromUnpacked(h plumbing.Hash) (obj plumbing.EncodedOb
 
 	s.objectCache.Put(obj)
 
-	_, err = io.Copy(w, r)
+	bufp := copyBufferPool.Get().(*[]byte)
+	buf := *bufp
+	_, err = io.CopyBuffer(w, r, buf)
+	copyBufferPool.Put(bufp)
+
 	return obj, err
 }
 
+var copyBufferPool = sync.Pool{
+	New: func() interface{} {
+		b := make([]byte, 32*1024)
+		return &b
+	},
+}
+
 // Get returns the object with the given hash, by searching for it in
 // the packfile.
 func (s *ObjectStorage) getFromPackfile(h plumbing.Hash, canBeDelta bool) (
@@ -595,6 +613,7 @@ func (s *ObjectStorage) buildPackfileIters(
 			return newPackfileIter(
 				s.dir.Fs(), pack, t, seen, s.index[h],
 				s.objectCache, s.options.KeepDescriptors,
+				s.options.LargeObjectThreshold,
 			)
 		},
 	}, nil
@@ -684,6 +703,7 @@ func NewPackfileIter(
 	idxFile billy.File,
 	t plumbing.ObjectType,
 	keepPack bool,
+	largeObjectThreshold int64,
 ) (storer.EncodedObjectIter, error) {
 	idx := idxfile.NewMemoryIndex()
 	if err := idxfile.NewDecoder(idxFile).Decode(idx); err != nil {
@@ -695,7 +715,7 @@ func NewPackfileIter(
 	}
 
 	seen := make(map[plumbing.Hash]struct{})
-	return newPackfileIter(fs, f, t, seen, idx, nil, keepPack)
+	return newPackfileIter(fs, f, t, seen, idx, nil, keepPack, largeObjectThreshold)
 }
 
 func newPackfileIter(
@@ -706,12 +726,13 @@ func newPackfileIter(
 	index idxfile.Index,
 	cache cache.Object,
 	keepPack bool,
+	largeObjectThreshold int64,
 ) (storer.EncodedObjectIter, error) {
 	var p *packfile.Packfile
 	if cache != nil {
-		p = packfile.NewPackfileWithCache(index, fs, f, cache)
+		p = packfile.NewPackfileWithCache(index, fs, f, cache, largeObjectThreshold)
 	} else {
-		p = packfile.NewPackfile(index, fs, f)
+		p = packfile.NewPackfile(index, fs, f, largeObjectThreshold)
 	}
 
 	iter, err := p.GetByType(t)
diff --git a/storage/filesystem/object_test.go b/storage/filesystem/object_test.go
index 22f5b0c2b..19a791464 100644
--- a/storage/filesystem/object_test.go
+++ b/storage/filesystem/object_test.go
@@ -71,7 +71,7 @@ func (s *FsSuite) TestGetFromPackfileKeepDescriptors(c *C) {
 		pack1, err := dg.ObjectPack(packfiles[0])
 		c.Assert(err, IsNil)
 
-		pack1.Seek(42, os.SEEK_SET)
+		pack1.Seek(42, io.SeekStart)
 
 		err = o.Close()
 		c.Assert(err, IsNil)
@@ -79,7 +79,7 @@ func (s *FsSuite) TestGetFromPackfileKeepDescriptors(c *C) {
 		pack2, err := dg.ObjectPack(packfiles[0])
 		c.Assert(err, IsNil)
 
-		offset, err := pack2.Seek(0, os.SEEK_CUR)
+		offset, err := pack2.Seek(0, io.SeekCurrent)
 		c.Assert(err, IsNil)
 		c.Assert(offset, Equals, int64(0))
 
@@ -107,6 +107,27 @@ func (s *FsSuite) TestGetFromPackfileMaxOpenDescriptors(c *C) {
 	c.Assert(err, IsNil)
 }
 
+func (s *FsSuite) TestGetFromPackfileMaxOpenDescriptorsLargeObjectThreshold(c *C) {
+	fs := fixtures.ByTag(".git").ByTag("multi-packfile").One().DotGit()
+	o := NewObjectStorageWithOptions(dotgit.New(fs), cache.NewObjectLRUDefault(), Options{
+		MaxOpenDescriptors:   1,
+		LargeObjectThreshold: 1,
+	})
+
+	expected := plumbing.NewHash("8d45a34641d73851e01d3754320b33bb5be3c4d3")
+	obj, err := o.getFromPackfile(expected, false)
+	c.Assert(err, IsNil)
+	c.Assert(obj.Hash(), Equals, expected)
+
+	expected = plumbing.NewHash("e9cfa4c9ca160546efd7e8582ec77952a27b17db")
+	obj, err = o.getFromPackfile(expected, false)
+	c.Assert(err, IsNil)
+	c.Assert(obj.Hash(), Equals, expected)
+
+	err = o.Close()
+	c.Assert(err, IsNil)
+}
+
 func (s *FsSuite) TestGetSizeOfObjectFile(c *C) {
 	fs := fixtures.ByTag(".git").ByTag("unpacked").One().DotGit()
 	o := NewObjectStorage(dotgit.New(fs), cache.NewObjectLRUDefault())
@@ -160,6 +181,21 @@ func (s *FsSuite) TestGetFromPackfileMultiplePackfiles(c *C) {
 	c.Assert(obj.Hash(), Equals, expected)
 }
 
+func (s *FsSuite) TestGetFromPackfileMultiplePackfilesLargeObjectThreshold(c *C) {
+	fs := fixtures.ByTag(".git").ByTag("multi-packfile").One().DotGit()
+	o := NewObjectStorageWithOptions(dotgit.New(fs), cache.NewObjectLRUDefault(), Options{LargeObjectThreshold: 1})
+
+	expected := plumbing.NewHash("8d45a34641d73851e01d3754320b33bb5be3c4d3")
+	obj, err := o.getFromPackfile(expected, false)
+	c.Assert(err, IsNil)
+	c.Assert(obj.Hash(), Equals, expected)
+
+	expected = plumbing.NewHash("e9cfa4c9ca160546efd7e8582ec77952a27b17db")
+	obj, err = o.getFromPackfile(expected, false)
+	c.Assert(err, IsNil)
+	c.Assert(obj.Hash(), Equals, expected)
+}
+
 func (s *FsSuite) TestIter(c *C) {
 	fixtures.ByTag(".git").ByTag("packfile").Test(c, func(f *fixtures.Fixture) {
 		fs := f.DotGit()
@@ -179,6 +215,25 @@ func (s *FsSuite) TestIter(c *C) {
 	})
 }
 
+func (s *FsSuite) TestIterLargeObjectThreshold(c *C) {
+	fixtures.ByTag(".git").ByTag("packfile").Test(c, func(f *fixtures.Fixture) {
+		fs := f.DotGit()
+		o := NewObjectStorageWithOptions(dotgit.New(fs), cache.NewObjectLRUDefault(), Options{LargeObjectThreshold: 1})
+
+		iter, err := o.IterEncodedObjects(plumbing.AnyObject)
+		c.Assert(err, IsNil)
+
+		var count int32
+		err = iter.ForEach(func(o plumbing.EncodedObject) error {
+			count++
+			return nil
+		})
+
+		c.Assert(err, IsNil)
+		c.Assert(count, Equals, f.ObjectsCount)
+	})
+}
+
 func (s *FsSuite) TestIterWithType(c *C) {
 	fixtures.ByTag(".git").Test(c, func(f *fixtures.Fixture) {
 		for _, t := range objectTypes {
@@ -215,7 +270,7 @@ func (s *FsSuite) TestPackfileIter(c *C) {
 				idxf, err := dg.ObjectPackIdx(h)
 				c.Assert(err, IsNil)
 
-				iter, err := NewPackfileIter(fs, f, idxf, t, false)
+				iter, err := NewPackfileIter(fs, f, idxf, t, false, 0)
 				c.Assert(err, IsNil)
 
 				err = iter.ForEach(func(o plumbing.EncodedObject) error {
@@ -298,7 +353,7 @@ func (s *FsSuite) TestPackfileIterKeepDescriptors(c *C) {
 				idxf, err := dg.ObjectPackIdx(h)
 				c.Assert(err, IsNil)
 
-				iter, err := NewPackfileIter(fs, f, idxf, t, true)
+				iter, err := NewPackfileIter(fs, f, idxf, t, true, 0)
 				c.Assert(err, IsNil)
 
 				err = iter.ForEach(func(o plumbing.EncodedObject) error {
@@ -331,7 +386,7 @@ func (s *FsSuite) TestGetFromObjectFileSharedCache(c *C) {
 	c.Assert(err, IsNil)
 	c.Assert(obj.Hash(), Equals, expected)
 
-	obj, err = o2.EncodedObject(plumbing.CommitObject, expected)
+	_, err = o2.EncodedObject(plumbing.CommitObject, expected)
 	c.Assert(err, Equals, plumbing.ErrObjectNotFound)
 }
 
@@ -377,7 +432,7 @@ func BenchmarkPackfileIter(b *testing.B) {
 							b.Fatal(err)
 						}
 
-						iter, err := NewPackfileIter(fs, f, idxf, t, false)
+						iter, err := NewPackfileIter(fs, f, idxf, t, false, 0)
 						if err != nil {
 							b.Fatal(err)
 						}
@@ -425,7 +480,7 @@ func BenchmarkPackfileIterReadContent(b *testing.B) {
 							b.Fatal(err)
 						}
 
-						iter, err := NewPackfileIter(fs, f, idxf, t, false)
+						iter, err := NewPackfileIter(fs, f, idxf, t, false, 0)
 						if err != nil {
 							b.Fatal(err)
 						}
diff --git a/storage/filesystem/shallow.go b/storage/filesystem/shallow.go
index afb600cf2..ac48fdfbb 100644
--- a/storage/filesystem/shallow.go
+++ b/storage/filesystem/shallow.go
@@ -34,7 +34,7 @@ func (s *ShallowStorage) SetShallow(commits []plumbing.Hash) error {
 	return err
 }
 
-// Shallow return the shallow commits reading from shallo file from .git
+// Shallow returns the shallow commits reading from shallo file from .git
 func (s *ShallowStorage) Shallow() ([]plumbing.Hash, error) {
 	f, err := s.dir.Shallow()
 	if f == nil || err != nil {
diff --git a/storage/filesystem/storage.go b/storage/filesystem/storage.go
index 8b69b27b0..7e7a2c50f 100644
--- a/storage/filesystem/storage.go
+++ b/storage/filesystem/storage.go
@@ -34,6 +34,9 @@ type Options struct {
 	// MaxOpenDescriptors is the max number of file descriptors to keep
 	// open. If KeepDescriptors is true, all file descriptors will remain open.
 	MaxOpenDescriptors int
+	// LargeObjectThreshold maximum object size (in bytes) that will be read in to memory.
+	// If left unset or set to 0 there is no limit
+	LargeObjectThreshold int64
 }
 
 // NewStorage returns a new Storage backed by a given `fs.Filesystem` and cache.
diff --git a/storage/memory/storage.go b/storage/memory/storage.go
index a8e56697b..ef6a44551 100644
--- a/storage/memory/storage.go
+++ b/storage/memory/storage.go
@@ -193,7 +193,7 @@ func (o *ObjectStorage) DeleteOldObjectPackAndIndex(plumbing.Hash, time.Time) er
 	return nil
 }
 
-var errNotSupported = fmt.Errorf("Not supported")
+var errNotSupported = fmt.Errorf("not supported")
 
 func (o *ObjectStorage) LooseObjectTime(hash plumbing.Hash) (time.Time, error) {
 	return time.Time{}, errNotSupported
diff --git a/storage/transactional/config_test.go b/storage/transactional/config_test.go
index 1f3a572f4..34d7763f6 100644
--- a/storage/transactional/config_test.go
+++ b/storage/transactional/config_test.go
@@ -54,7 +54,7 @@ func (s *ConfigSuite) TestSetConfigTemporal(c *C) {
 
 	cfg, err = cs.Config()
 	c.Assert(err, IsNil)
-	c.Assert(temporalCfg.Core.Worktree, Equals, "bar")
+	c.Assert(cfg.Core.Worktree, Equals, "bar")
 }
 
 func (s *ConfigSuite) TestCommit(c *C) {
diff --git a/storage/transactional/reference.go b/storage/transactional/reference.go
index 3b009e2e6..1c0930755 100644
--- a/storage/transactional/reference.go
+++ b/storage/transactional/reference.go
@@ -15,9 +15,6 @@ type ReferenceStorage struct {
 	// commit is requested, the entries are added when RemoveReference is called
 	// and deleted if SetReference is called.
 	deleted map[plumbing.ReferenceName]struct{}
-	// packRefs if true PackRefs is going to be called in the based storer when
-	// commit is called.
-	packRefs bool
 }
 
 // NewReferenceStorage returns a new ReferenceStorer based on a base storer and
@@ -108,7 +105,6 @@ func (r ReferenceStorage) CountLooseRefs() (int, error) {
 
 // PackRefs honors the storer.ReferenceStorer interface.
 func (r ReferenceStorage) PackRefs() error {
-	r.packRefs = true
 	return nil
 }
 
diff --git a/utils/ioutil/common.go b/utils/ioutil/common.go
index b52e85a38..b0ace4e62 100644
--- a/utils/ioutil/common.go
+++ b/utils/ioutil/common.go
@@ -55,6 +55,28 @@ func NewReadCloser(r io.Reader, c io.Closer) io.ReadCloser {
 	return &readCloser{Reader: r, closer: c}
 }
 
+type readCloserCloser struct {
+	io.ReadCloser
+	closer func() error
+}
+
+func (r *readCloserCloser) Close() (err error) {
+	defer func() {
+		if err == nil {
+			err = r.closer()
+			return
+		}
+		_ = r.closer()
+	}()
+	return r.ReadCloser.Close()
+}
+
+// NewReadCloserWithCloser creates an `io.ReadCloser` with the given `io.ReaderCloser` and
+// `io.Closer` that ensures that the closer is closed on close
+func NewReadCloserWithCloser(r io.ReadCloser, c func() error) io.ReadCloser {
+	return &readCloserCloser{ReadCloser: r, closer: c}
+}
+
 type writeCloser struct {
 	io.Writer
 	closer io.Closer
@@ -82,6 +104,24 @@ func WriteNopCloser(w io.Writer) io.WriteCloser {
 	return writeNopCloser{w}
 }
 
+type readerAtAsReader struct {
+	io.ReaderAt
+	offset int64
+}
+
+func (r *readerAtAsReader) Read(bs []byte) (int, error) {
+	n, err := r.ReaderAt.ReadAt(bs, r.offset)
+	r.offset += int64(n)
+	return n, err
+}
+
+func NewReaderUsingReaderAt(r io.ReaderAt, offset int64) io.Reader {
+	return &readerAtAsReader{
+		ReaderAt: r,
+		offset:   offset,
+	}
+}
+
 // CheckClose calls Close on the given io.Closer. If the given *error points to
 // nil, it will be assigned the error returned by Close. Otherwise, any error
 // returned by Close will be ignored. CheckClose is usually called with defer.
diff --git a/utils/merkletrie/difftree.go b/utils/merkletrie/difftree.go
index bd084b2ab..9f5145a26 100644
--- a/utils/merkletrie/difftree.go
+++ b/utils/merkletrie/difftree.go
@@ -304,13 +304,38 @@ func DiffTreeContext(ctx context.Context, fromTree, toTree noder.Noder,
 				return nil, err
 			}
 		case onlyToRemains:
-			if err = ret.AddRecursiveInsert(to); err != nil {
-				return nil, err
+			if to.Skip() {
+				if err = ret.AddRecursiveDelete(to); err != nil {
+					return nil, err
+				}
+			} else {
+				if err = ret.AddRecursiveInsert(to); err != nil {
+					return nil, err
+				}
 			}
 			if err = ii.nextTo(); err != nil {
 				return nil, err
 			}
 		case bothHaveNodes:
+			if from.Skip() {
+				if err = ret.AddRecursiveDelete(from); err != nil {
+					return nil, err
+				}
+				if err := ii.nextBoth(); err != nil {
+					return nil, err
+				}
+				break
+			}
+			if to.Skip() {
+				if err = ret.AddRecursiveDelete(to); err != nil {
+					return nil, err
+				}
+				if err := ii.nextBoth(); err != nil {
+					return nil, err
+				}
+				break
+			}
+
 			if err = diffNodes(&ret, ii); err != nil {
 				return nil, err
 			}
diff --git a/utils/merkletrie/filesystem/node.go b/utils/merkletrie/filesystem/node.go
index 2fc3d7a63..ad169ff4a 100644
--- a/utils/merkletrie/filesystem/node.go
+++ b/utils/merkletrie/filesystem/node.go
@@ -61,6 +61,10 @@ func (n *node) IsDir() bool {
 	return n.isDir
 }
 
+func (n *node) Skip() bool {
+	return false
+}
+
 func (n *node) Children() ([]noder.Noder, error) {
 	if err := n.calculateChildren(); err != nil {
 		return nil, err
diff --git a/utils/merkletrie/index/node.go b/utils/merkletrie/index/node.go
index d05b0c694..c1809f7ec 100644
--- a/utils/merkletrie/index/node.go
+++ b/utils/merkletrie/index/node.go
@@ -19,6 +19,7 @@ type node struct {
 	entry    *index.Entry
 	children []noder.Noder
 	isDir    bool
+	skip     bool
 }
 
 // NewRootNode returns the root node of a computed tree from a index.Index,
@@ -39,7 +40,7 @@ func NewRootNode(idx *index.Index) noder.Noder {
 				continue
 			}
 
-			n := &node{path: fullpath}
+			n := &node{path: fullpath, skip: e.SkipWorktree}
 			if fullpath == e.Name {
 				n.entry = e
 			} else {
@@ -58,6 +59,10 @@ func (n *node) String() string {
 	return n.path
 }
 
+func (n *node) Skip() bool {
+	return n.skip
+}
+
 // Hash the hash of a filesystem is a 24-byte slice, is the result of
 // concatenating the computed plumbing.Hash of the file as a Blob and its
 // plumbing.FileMode; that way the difftree algorithm will detect changes in the
diff --git a/utils/merkletrie/internal/fsnoder/dir.go b/utils/merkletrie/internal/fsnoder/dir.go
index 20a2aeebb..3a4c2424e 100644
--- a/utils/merkletrie/internal/fsnoder/dir.go
+++ b/utils/merkletrie/internal/fsnoder/dir.go
@@ -112,6 +112,10 @@ func (d *dir) NumChildren() (int, error) {
 	return len(d.children), nil
 }
 
+func (d *dir) Skip() bool {
+	return false
+}
+
 const (
 	dirStartMark  = '('
 	dirEndMark    = ')'
diff --git a/utils/merkletrie/internal/fsnoder/file.go b/utils/merkletrie/internal/fsnoder/file.go
index d53643f1a..0bb908b7a 100644
--- a/utils/merkletrie/internal/fsnoder/file.go
+++ b/utils/merkletrie/internal/fsnoder/file.go
@@ -55,6 +55,10 @@ func (f *file) NumChildren() (int, error) {
 	return 0, nil
 }
 
+func (f *file) Skip() bool {
+	return false
+}
+
 const (
 	fileStartMark = '<'
 	fileEndMark   = '>'
diff --git a/utils/merkletrie/noder/noder.go b/utils/merkletrie/noder/noder.go
index d6b3de4ad..6d22b8c14 100644
--- a/utils/merkletrie/noder/noder.go
+++ b/utils/merkletrie/noder/noder.go
@@ -53,6 +53,7 @@ type Noder interface {
 	// implement NumChildren in O(1) while Children is usually more
 	// complex.
 	NumChildren() (int, error)
+	Skip()	bool
 }
 
 // NoChildren represents the children of a noder without children.
diff --git a/utils/merkletrie/noder/noder_test.go b/utils/merkletrie/noder/noder_test.go
index 5e014fe9b..c1af99843 100644
--- a/utils/merkletrie/noder/noder_test.go
+++ b/utils/merkletrie/noder/noder_test.go
@@ -25,6 +25,7 @@ func (n noderMock) Name() string               { return n.name }
 func (n noderMock) IsDir() bool                { return n.isDir }
 func (n noderMock) Children() ([]Noder, error) { return n.children, nil }
 func (n noderMock) NumChildren() (int, error)  { return len(n.children), nil }
+func (n noderMock) Skip() bool                 { return false }
 
 // Returns a sequence with the noders 3, 2, and 1 from the
 // following diagram:
@@ -57,20 +58,6 @@ func childrenFixture() []Noder {
 	return []Noder{c1, c2}
 }
 
-// Returns the same as nodersFixture but sorted by name, this is: "1",
-// "2" and then "3".
-func sortedNodersFixture() []Noder {
-	n1 := &noderMock{
-		name:     "1",
-		hash:     []byte{0x00, 0x01, 0x02},
-		isDir:    true,
-		children: childrenFixture(),
-	}
-	n2 := &noderMock{name: "2"}
-	n3 := &noderMock{name: "3"}
-	return []Noder{n1, n2, n3} // the same as nodersFixture but sorted by name
-}
-
 // returns nodersFixture as the path of "1".
 func pathFixture() Path {
 	return Path(nodersFixture())
diff --git a/utils/merkletrie/noder/path.go b/utils/merkletrie/noder/path.go
index 1c7ef54ee..6c1d36332 100644
--- a/utils/merkletrie/noder/path.go
+++ b/utils/merkletrie/noder/path.go
@@ -15,6 +15,14 @@ import (
 // not be used.
 type Path []Noder
 
+func (p Path) Skip() bool {
+	if len(p) > 0 {
+		return p.Last().Skip()
+	}
+
+	return false
+}
+
 // String returns the full path of the final noder as a string, using
 // "/" as the separator.
 func (p Path) String() string {
diff --git a/utils/sync/bufio.go b/utils/sync/bufio.go
new file mode 100644
index 000000000..5009ea804
--- /dev/null
+++ b/utils/sync/bufio.go
@@ -0,0 +1,29 @@
+package sync
+
+import (
+	"bufio"
+	"io"
+	"sync"
+)
+
+var bufioReader = sync.Pool{
+	New: func() interface{} {
+		return bufio.NewReader(nil)
+	},
+}
+
+// GetBufioReader returns a *bufio.Reader that is managed by a sync.Pool.
+// Returns a bufio.Reader that is resetted with reader and ready for use.
+//
+// After use, the *bufio.Reader should be put back into the sync.Pool
+// by calling PutBufioReader.
+func GetBufioReader(reader io.Reader) *bufio.Reader {
+	r := bufioReader.Get().(*bufio.Reader)
+	r.Reset(reader)
+	return r
+}
+
+// PutBufioReader puts reader back into its sync.Pool.
+func PutBufioReader(reader *bufio.Reader) {
+	bufioReader.Put(reader)
+}
diff --git a/utils/sync/bufio_test.go b/utils/sync/bufio_test.go
new file mode 100644
index 000000000..e70f3d803
--- /dev/null
+++ b/utils/sync/bufio_test.go
@@ -0,0 +1,26 @@
+package sync
+
+import (
+	"io"
+	"strings"
+	"testing"
+)
+
+func TestGetAndPutBufioReader(t *testing.T) {
+	wanted := "someinput"
+	r := GetBufioReader(strings.NewReader(wanted))
+	if r == nil {
+		t.Error("nil was not expected")
+	}
+
+	got, err := r.ReadString(0)
+	if err != nil && err != io.EOF {
+		t.Errorf("unexpected error reading string: %v", err)
+	}
+
+	if wanted != got {
+		t.Errorf("wanted %q got %q", wanted, got)
+	}
+
+	PutBufioReader(r)
+}
diff --git a/utils/sync/bytes.go b/utils/sync/bytes.go
new file mode 100644
index 000000000..dd06fc0bc
--- /dev/null
+++ b/utils/sync/bytes.go
@@ -0,0 +1,51 @@
+package sync
+
+import (
+	"bytes"
+	"sync"
+)
+
+var (
+	byteSlice = sync.Pool{
+		New: func() interface{} {
+			b := make([]byte, 16*1024)
+			return &b
+		},
+	}
+	bytesBuffer = sync.Pool{
+		New: func() interface{} {
+			return bytes.NewBuffer(nil)
+		},
+	}
+)
+
+// GetByteSlice returns a *[]byte that is managed by a sync.Pool.
+// The initial slice length will be 16384 (16kb).
+//
+// After use, the *[]byte should be put back into the sync.Pool
+// by calling PutByteSlice.
+func GetByteSlice() *[]byte {
+	buf := byteSlice.Get().(*[]byte)
+	return buf
+}
+
+// PutByteSlice puts buf back into its sync.Pool.
+func PutByteSlice(buf *[]byte) {
+	byteSlice.Put(buf)
+}
+
+// GetBytesBuffer returns a *bytes.Buffer that is managed by a sync.Pool.
+// Returns a buffer that is resetted and ready for use.
+//
+// After use, the *bytes.Buffer should be put back into the sync.Pool
+// by calling PutBytesBuffer.
+func GetBytesBuffer() *bytes.Buffer {
+	buf := bytesBuffer.Get().(*bytes.Buffer)
+	buf.Reset()
+	return buf
+}
+
+// PutBytesBuffer puts buf back into its sync.Pool.
+func PutBytesBuffer(buf *bytes.Buffer) {
+	bytesBuffer.Put(buf)
+}
diff --git a/utils/sync/bytes_test.go b/utils/sync/bytes_test.go
new file mode 100644
index 000000000..b233429ce
--- /dev/null
+++ b/utils/sync/bytes_test.go
@@ -0,0 +1,49 @@
+package sync
+
+import (
+	"testing"
+)
+
+func TestGetAndPutBytesBuffer(t *testing.T) {
+	buf := GetBytesBuffer()
+	if buf == nil {
+		t.Error("nil was not expected")
+	}
+
+	initialLen := buf.Len()
+	buf.Grow(initialLen * 2)
+	grownLen := buf.Len()
+
+	PutBytesBuffer(buf)
+
+	buf = GetBytesBuffer()
+	if buf.Len() != grownLen {
+		t.Error("bytes buffer was not reused")
+	}
+
+	buf2 := GetBytesBuffer()
+	if buf2.Len() != initialLen {
+		t.Errorf("new bytes buffer length: wanted %d got %d", initialLen, buf2.Len())
+	}
+}
+
+func TestGetAndPutByteSlice(t *testing.T) {
+	slice := GetByteSlice()
+	if slice == nil {
+		t.Error("nil was not expected")
+	}
+
+	wanted := 16 * 1024
+	got := len(*slice)
+	if wanted != got {
+		t.Errorf("byte slice length: wanted %d got %d", wanted, got)
+	}
+
+	newByteSlice := make([]byte, wanted*2)
+	PutByteSlice(&newByteSlice)
+
+	newSlice := GetByteSlice()
+	if len(*newSlice) != len(newByteSlice) {
+		t.Error("byte slice was not reused")
+	}
+}
diff --git a/utils/sync/zlib.go b/utils/sync/zlib.go
new file mode 100644
index 000000000..c61388595
--- /dev/null
+++ b/utils/sync/zlib.go
@@ -0,0 +1,74 @@
+package sync
+
+import (
+	"bytes"
+	"compress/zlib"
+	"io"
+	"sync"
+)
+
+var (
+	zlibInitBytes = []byte{0x78, 0x9c, 0x01, 0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0x01}
+	zlibReader    = sync.Pool{
+		New: func() interface{} {
+			r, _ := zlib.NewReader(bytes.NewReader(zlibInitBytes))
+			return ZLibReader{
+				Reader: r.(zlibReadCloser),
+			}
+		},
+	}
+	zlibWriter = sync.Pool{
+		New: func() interface{} {
+			return zlib.NewWriter(nil)
+		},
+	}
+)
+
+type zlibReadCloser interface {
+	io.ReadCloser
+	zlib.Resetter
+}
+
+type ZLibReader struct {
+	dict   *[]byte
+	Reader zlibReadCloser
+}
+
+// GetZlibReader returns a ZLibReader that is managed by a sync.Pool.
+// Returns a ZLibReader that is resetted using a dictionary that is
+// also managed by a sync.Pool.
+//
+// After use, the ZLibReader should be put back into the sync.Pool
+// by calling PutZlibReader.
+func GetZlibReader(r io.Reader) (ZLibReader, error) {
+	z := zlibReader.Get().(ZLibReader)
+	z.dict = GetByteSlice()
+
+	err := z.Reader.Reset(r, *z.dict)
+
+	return z, err
+}
+
+// PutZlibReader puts z back into its sync.Pool, first closing the reader.
+// The Byte slice dictionary is also put back into its sync.Pool.
+func PutZlibReader(z ZLibReader) {
+	z.Reader.Close()
+	PutByteSlice(z.dict)
+	zlibReader.Put(z)
+}
+
+// GetZlibWriter returns a *zlib.Writer that is managed by a sync.Pool.
+// Returns a writer that is resetted with w and ready for use.
+//
+// After use, the *zlib.Writer should be put back into the sync.Pool
+// by calling PutZlibWriter.
+func GetZlibWriter(w io.Writer) *zlib.Writer {
+	z := zlibWriter.Get().(*zlib.Writer)
+	z.Reset(w)
+	return z
+}
+
+// PutZlibWriter puts w back into its sync.Pool.
+func PutZlibWriter(w *zlib.Writer) {
+	zlibWriter.Put(w)
+}
diff --git a/utils/sync/zlib_test.go b/utils/sync/zlib_test.go
new file mode 100644
index 000000000..b736fb221
--- /dev/null
+++ b/utils/sync/zlib_test.go
@@ -0,0 +1,74 @@
+package sync
+
+import (
+	"bytes"
+	"compress/zlib"
+	"io"
+	"testing"
+)
+
+func TestGetAndPutZlibReader(t *testing.T) {
+	_, err := GetZlibReader(bytes.NewReader(zlibInitBytes))
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+
+	dict := &[]byte{}
+	reader := FakeZLibReader{}
+	PutZlibReader(ZLibReader{dict: dict, Reader: &reader})
+
+	if !reader.wasClosed {
+		t.Errorf("reader was not closed")
+	}
+
+	z2, err := GetZlibReader(bytes.NewReader(zlibInitBytes))
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+
+	if dict != z2.dict {
+		t.Errorf("zlib dictionary was not reused")
+	}
+
+	if &reader != z2.Reader {
+		t.Errorf("zlib reader was not reused")
+	}
+
+	if !reader.wasReset {
+		t.Errorf("reader was not reset")
+	}
+}
+
+func TestGetAndPutZlibWriter(t *testing.T) {
+	w := GetZlibWriter(nil)
+	if w == nil {
+		t.Errorf("nil was not expected")
+	}
+
+	newW := zlib.NewWriter(nil)
+	PutZlibWriter(newW)
+
+	w2 := GetZlibWriter(nil)
+	if w2 != newW {
+		t.Errorf("zlib writer was not reused")
+	}
+}
+
+type FakeZLibReader struct {
+	wasClosed bool
+	wasReset  bool
+}
+
+func (f *FakeZLibReader) Reset(r io.Reader, dict []byte) error {
+	f.wasReset = true
+	return nil
+}
+
+func (f *FakeZLibReader) Read(p []byte) (n int, err error) {
+	return 0, nil
+}
+
+func (f *FakeZLibReader) Close() error {
+	f.wasClosed = true
+	return nil
+}
diff --git a/worktree.go b/worktree.go
index f23d9f170..02f90a9e6 100644
--- a/worktree.go
+++ b/worktree.go
@@ -9,8 +9,9 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
-	"sync"
 
+	"github.com/go-git/go-billy/v5"
+	"github.com/go-git/go-billy/v5/util"
 	"github.com/go-git/go-git/v5/config"
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/plumbing/filemode"
@@ -20,9 +21,7 @@ import (
 	"github.com/go-git/go-git/v5/plumbing/storer"
 	"github.com/go-git/go-git/v5/utils/ioutil"
 	"github.com/go-git/go-git/v5/utils/merkletrie"
-
-	"github.com/go-git/go-billy/v5"
-	"github.com/go-git/go-billy/v5/util"
+	"github.com/go-git/go-git/v5/utils/sync"
 )
 
 var (
@@ -73,6 +72,7 @@ func (w *Worktree) PullContext(ctx context.Context, o *PullOptions) error {
 
 	fetchHead, err := remote.fetch(ctx, &FetchOptions{
 		RemoteName:      o.RemoteName,
+		RemoteURL:       o.RemoteURL,
 		Depth:           o.Depth,
 		Auth:            o.Auth,
 		Progress:        o.Progress,
@@ -182,6 +182,10 @@ func (w *Worktree) Checkout(opts *CheckoutOptions) error {
 		return err
 	}
 
+	if len(opts.SparseCheckoutDirectories) > 0 {
+		return w.ResetSparsely(ro, opts.SparseCheckoutDirectories)
+	}
+
 	return w.Reset(ro)
 }
 func (w *Worktree) createBranch(opts *CheckoutOptions) error {
@@ -262,8 +266,7 @@ func (w *Worktree) setHEADToBranch(branch plumbing.ReferenceName, commit plumbin
 	return w.r.Storer.SetReference(head)
 }
 
-// Reset the worktree to a specified state.
-func (w *Worktree) Reset(opts *ResetOptions) error {
+func (w *Worktree) ResetSparsely(opts *ResetOptions, dirs []string) error {
 	if err := opts.Validate(w.r); err != nil {
 		return err
 	}
@@ -293,7 +296,7 @@ func (w *Worktree) Reset(opts *ResetOptions) error {
 	}
 
 	if opts.Mode == MixedReset || opts.Mode == MergeReset || opts.Mode == HardReset {
-		if err := w.resetIndex(t); err != nil {
+		if err := w.resetIndex(t, dirs); err != nil {
 			return err
 		}
 	}
@@ -307,8 +310,17 @@ func (w *Worktree) Reset(opts *ResetOptions) error {
 	return nil
 }
 
-func (w *Worktree) resetIndex(t *object.Tree) error {
+// Reset the worktree to a specified state.
+func (w *Worktree) Reset(opts *ResetOptions) error {
+	return w.ResetSparsely(opts, nil)
+}
+
+func (w *Worktree) resetIndex(t *object.Tree, dirs []string) error {
 	idx, err := w.r.Storer.Index()
+	if len(dirs) > 0 {
+		idx.SkipUnless(dirs)
+	}
+
 	if err != nil {
 		return err
 	}
@@ -520,12 +532,6 @@ func (w *Worktree) checkoutChangeRegularFile(name string,
 	return nil
 }
 
-var copyBufferPool = sync.Pool{
-	New: func() interface{} {
-		return make([]byte, 32*1024)
-	},
-}
-
 func (w *Worktree) checkoutFile(f *object.File) (err error) {
 	mode, err := f.Mode.ToOSFileMode()
 	if err != nil {
@@ -549,9 +555,9 @@ func (w *Worktree) checkoutFile(f *object.File) (err error) {
 	}
 
 	defer ioutil.CheckClose(to, &err)
-	buf := copyBufferPool.Get().([]byte)
-	_, err = io.CopyBuffer(to, from, buf)
-	copyBufferPool.Put(buf)
+	buf := sync.GetByteSlice()
+	_, err = io.CopyBuffer(to, from, *buf)
+	sync.PutByteSlice(buf)
 	return
 }
 
diff --git a/worktree_bsd.go b/worktree_bsd.go
index d4ea32758..d4682eb83 100644
--- a/worktree_bsd.go
+++ b/worktree_bsd.go
@@ -12,7 +12,7 @@ import (
 func init() {
 	fillSystemInfo = func(e *index.Entry, sys interface{}) {
 		if os, ok := sys.(*syscall.Stat_t); ok {
-			e.CreatedAt = time.Unix(int64(os.Atimespec.Sec), int64(os.Atimespec.Nsec))
+			e.CreatedAt = time.Unix(os.Atimespec.Unix())
 			e.Dev = uint32(os.Dev)
 			e.Inode = uint32(os.Ino)
 			e.GID = os.Gid
diff --git a/worktree_commit_test.go b/worktree_commit_test.go
index 65d4b695d..097c6e5d3 100644
--- a/worktree_commit_test.go
+++ b/worktree_commit_test.go
@@ -212,10 +212,10 @@ func (s *WorktreeSuite) TestCommitTreeSort(c *C) {
 	defer clean()
 
 	st := filesystem.NewStorage(fs, cache.NewObjectLRUDefault())
-	r, err := Init(st, nil)
+	_, err := Init(st, nil)
 	c.Assert(err, IsNil)
 
-	r, _ = Clone(memory.NewStorage(), memfs.New(), &CloneOptions{
+	r, _ := Clone(memory.NewStorage(), memfs.New(), &CloneOptions{
 		URL: fs.Root(),
 	})
 
@@ -296,6 +296,7 @@ func (s *WorktreeSuite) TestJustStoreObjectsNotAlreadyStored(c *C) {
 		All:    true,
 		Author: defaultSignature(),
 	})
+	c.Assert(err, IsNil)
 	c.Assert(hash, Equals, plumbing.NewHash("97c0c5177e6ac57d10e8ea0017f2d39b91e2b364"))
 
 	// Step 3: Check
diff --git a/worktree_linux.go b/worktree_linux.go
index cf0db2524..6fcace2f9 100644
--- a/worktree_linux.go
+++ b/worktree_linux.go
@@ -12,7 +12,7 @@ import (
 func init() {
 	fillSystemInfo = func(e *index.Entry, sys interface{}) {
 		if os, ok := sys.(*syscall.Stat_t); ok {
-			e.CreatedAt = time.Unix(int64(os.Ctim.Sec), int64(os.Ctim.Nsec))
+			e.CreatedAt = time.Unix(os.Ctim.Unix())
 			e.Dev = uint32(os.Dev)
 			e.Inode = uint32(os.Ino)
 			e.GID = os.Gid
diff --git a/worktree_test.go b/worktree_test.go
index 79cbefd77..4a1412693 100644
--- a/worktree_test.go
+++ b/worktree_test.go
@@ -10,6 +10,7 @@ import (
 	"path/filepath"
 	"regexp"
 	"runtime"
+	"strings"
 	"testing"
 	"time"
 
@@ -183,7 +184,7 @@ func (s *WorktreeSuite) TestPullInSingleBranch(c *C) {
 	c.Assert(err, IsNil)
 	c.Assert(branch.Hash().String(), Equals, "6ecf0ef2c2dffb796033e5a02219af86ec6584e5")
 
-	branch, err = r.Reference("refs/remotes/foo/branch", false)
+	_, err = r.Reference("refs/remotes/foo/branch", false)
 	c.Assert(err, NotNil)
 
 	storage := r.Storer.(*memory.Storage)
@@ -417,6 +418,37 @@ func (s *WorktreeSuite) TestCheckoutSymlink(c *C) {
 	c.Assert(err, IsNil)
 }
 
+func (s *WorktreeSuite) TestCheckoutSparse(c *C) {
+	fs := memfs.New()
+	r, err := Clone(memory.NewStorage(), fs, &CloneOptions{
+		URL: s.GetBasicLocalRepositoryURL(),
+	})
+	c.Assert(err, IsNil)
+
+	w, err := r.Worktree()
+	c.Assert(err, IsNil)
+
+	sparseCheckoutDirectories := []string{"go", "json", "php"}
+	c.Assert(w.Checkout(&CheckoutOptions{
+		SparseCheckoutDirectories: sparseCheckoutDirectories,
+	}), IsNil)
+
+	fis, err := fs.ReadDir("/")
+	c.Assert(err, IsNil)
+
+	for _, fi := range fis {
+		c.Assert(fi.IsDir(), Equals, true)
+		var oneOfSparseCheckoutDirs bool
+
+		for _, sparseCheckoutDirectory := range sparseCheckoutDirectories {
+			if strings.HasPrefix(fi.Name(), sparseCheckoutDirectory) {
+				oneOfSparseCheckoutDirs = true
+			}
+		}
+		c.Assert(oneOfSparseCheckoutDirs, Equals, true)
+	}
+}
+
 func (s *WorktreeSuite) TestFilenameNormalization(c *C) {
 	if runtime.GOOS == "windows" {
 		c.Skip("windows paths may contain non utf-8 sequences")
@@ -555,6 +587,7 @@ func (s *WorktreeSuite) TestCheckoutRelativePathSubmoduleInitialized(c *C) {
 
 	// test submodule path
 	modules, err := w.readGitmodulesFile()
+	c.Assert(err, IsNil)
 
 	c.Assert(modules.Submodules["basic"].URL, Equals, "../basic.git")
 	c.Assert(modules.Submodules["itself"].URL, Equals, "../submodule.git")
diff --git a/worktree_unix_other.go b/worktree_unix_other.go
index f45966be9..5b16e70b7 100644
--- a/worktree_unix_other.go
+++ b/worktree_unix_other.go
@@ -12,7 +12,7 @@ import (
 func init() {
 	fillSystemInfo = func(e *index.Entry, sys interface{}) {
 		if os, ok := sys.(*syscall.Stat_t); ok {
-			e.CreatedAt = time.Unix(int64(os.Atim.Sec), int64(os.Atim.Nsec))
+			e.CreatedAt = time.Unix(os.Atim.Unix())
 			e.Dev = uint32(os.Dev)
 			e.Inode = uint32(os.Ino)
 			e.GID = os.Gid