[Python-checkins] Add whatsnew note for GH-22904 (#24672)

[tim-one]

https://github.com/python/cpython/commit/e8f5ddd33e44dae4e0121f87a7bf92d754807e49
commit: e8f5ddd33e44dae4e0121f87a7bf92d754807e49
branch: master
author: Dennis Sweeney <36520290+sweeneyde at users.noreply.github.com>
committer: tim-one <tim.peters at gmail.com>
date: 2021-02-28T15:32:04-06:00
summary:

Add whatsnew note for GH-22904 (#24672)

files:
M Doc/whatsnew/3.10.rst

diff --git a/Doc/whatsnew/3.10.rst b/Doc/whatsnew/3.10.rst
index 310554eabe670..12db463008132 100644
--- a/Doc/whatsnew/3.10.rst
+++ b/Doc/whatsnew/3.10.rst
@@ -615,6 +615,11 @@ Optimizations
   bytecode level.  It is now around 100% faster to create a function with parameter
   annotations.  (Contributed by Yurii Karabas and Inada Naoki in :issue:`42202`)
 
+* Substring search functions such as ``str1 in str2`` and ``str2.find(str1)``
+  now sometimes use Crochemore & Perrin's "Two-Way" string searching
+  algorithm to avoid quadratic behavior on long strings.  (Contributed
+  by Dennis Sweeney in :issue:`41972`)
+
 Deprecated
 ==========