Bug Report or Feature Request (mark with an x)

- [ x] bug report -> please search issues before submitting
- [ ] feature request

Versions.

ng --version
_ _ ____ _ ___
/ \ _ __ __ _ _ | | __ _ _ __ / | | | |
/ △ \ | ' \ / _ | | | | |/ _ | '| | | | | | |
/ ___ | | | | (| | || | | (| | | | || | | |
// __| ||_, |_,||_,|| _|||
|___/
@angular/cli: 1.1.0
node: 7.9.0
os: win32 x64 (Win 10 Enterpirise - 16Gig , i7)
@angular/animations: 4.0.0
@angular/common: 4.0.0
@angular/compiler: 4.0.0
@angular/core: 4.0.0
@angular/forms: 4.0.0
@angular/http: 4.0.0
@angular/platform-browser: 4.0.0
@angular/platform-browser-dynamic: 4.0.0
@angular/router: 4.0.0
@angular/cli: 1.1.0
@angular/compiler-cli: 4.0.0
@angular/language-service: 4.0.0

Repro steps.

$ ng build --prod --aot=false -ec --sourcemap=false
Hash: 552d9867ececa788ac3a
Time: 670222ms
chunk {0} polyfills.d77767cee98c83f90386.bundle.js (polyfills) 294 kB {5} [initial] [rendered]
chunk {1} main.255e1d27fe4d40b56ab2.bundle.js (main) 1.51 MB {4} [initial] [rendered]
chunk {2} scripts.45a4574f31d7b91e5a5e.bundle.js (scripts) 3.88 MB {5} [initial] [rendered]
chunk {3} styles.ac17d766c993c4027892.bundle.css (styles) 228 bytes {5} [initial] [rendered]
chunk {4} vendor.86c029ec4598fb674488.bundle.js (vendor) 8.23 MB [initial] [rendered]
chunk {5} inline.750f0337ff0a9bee9813.bundle.js (inline) 0 bytes [entry] [rendered]

ng build --aot -ec -sm
Hash: 24f744145f250126e699
Time: 62809ms
chunk {0} polyfills.bundle.js, polyfills.bundle.js.map (polyfills) 294 kB {5} [initial] [rendered]
chunk {1} main.bundle.js, main.bundle.js.map (main) 3.07 MB {4} [initial] [rendered]
chunk {2} scripts.bundle.js, scripts.bundle.js.map (scripts) 3.88 MB {5} [initial] [rendered]
chunk {3} styles.bundle.css, styles.bundle.css.map (styles) 228 bytes {5} [initial] [rendered]
chunk {4} vendor.bundle.js, vendor.bundle.js.map (vendor) 7.37 MB [initial] [rendered]
chunk {5} inline.bundle.js, inline.bundle.js.map (inline) 0 bytes [entry] [rendered]

670222ms vs 62809ms is a huge difference

The log given by the failure.

There is no failure , the build takes a very long time to complete its stuck at
92% chunk asset optimization and then we have to wait for 10-15 mins to get the build completed.
I have disabled aot and sourcemaps, still the speed is very slow.

Desired functionality.

build should have similar time that to of ng build -aot

Any help and guidance to reduce will be helpful.