From f1b0a28574a06f94ae2369f3c8c017b081bf5de9 Mon Sep 17 00:00:00 2001
From: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com>
Date: Mon, 30 Sep 2024 22:25:06 +0200
Subject: [PATCH] MNT: Fix double evaluation of _LazyTickList

Closes #28908.

The final instance.majorTicks list must be assigned after running
`_get_tick()` because that may call `reset_ticks()`, which invalidates
a previous set list. We still temporarily assign an empty tick list
to instance.majorTicks, because `_get_tick()` may rely on that
attibute to exist.
---
 doc/users/next_whats_new/axes_creation_speedup.rst |  4 ++++
 lib/matplotlib/axis.py                             | 10 ++++++----
 2 files changed, 10 insertions(+), 4 deletions(-)
 create mode 100644 doc/users/next_whats_new/axes_creation_speedup.rst

diff --git a/doc/users/next_whats_new/axes_creation_speedup.rst b/doc/users/next_whats_new/axes_creation_speedup.rst
new file mode 100644
index 000000000000..c9eaa48c0060
--- /dev/null
+++ b/doc/users/next_whats_new/axes_creation_speedup.rst
@@ -0,0 +1,4 @@
+Axes creation speedup
+~~~~~~~~~~~~~~~~~~~~~
+
+Creating an Axes is now 20-25% faster due to internal optimizations.
diff --git a/lib/matplotlib/axis.py b/lib/matplotlib/axis.py
index cbf7928ec44e..d7ba29e1d595 100644
--- a/lib/matplotlib/axis.py
+++ b/lib/matplotlib/axis.py
@@ -538,17 +538,19 @@ def __get__(self, instance, owner):
             # instance._get_tick() can itself try to access the majorTicks
             # attribute (e.g. in certain projection classes which override
             # e.g. get_xaxis_text1_transform).  In order to avoid infinite
-            # recursion, first set the majorTicks on the instance to an empty
-            # list, then create the tick and append it.
+            # recursion, first set the majorTicks on the instance temporarily
+            # to an empty lis. Then create the tick; note that _get_tick()
+            # may call reset_ticks(). Therefore, the final tick list is
+            # created and assigned afterwards.
             if self._major:
                 instance.majorTicks = []
                 tick = instance._get_tick(major=True)
-                instance.majorTicks.append(tick)
+                instance.majorTicks = [tick]
                 return instance.majorTicks
             else:
                 instance.minorTicks = []
                 tick = instance._get_tick(major=False)
-                instance.minorTicks.append(tick)
+                instance.minorTicks = [tick]
                 return instance.minorTicks