From: Ken Jin <kenjin@python.org>
Date: Mon, 22 Dec 2025 23:56:26 +0000 (+0800)
Subject: gh-139922: Add tail call for MSVC for whats new in 3.15 (GH-143087)
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=714037ba845a5a5168a7a8648befce203e2f0c24;p=thirdparty%2FPython%2Fcpython.git

gh-139922: Add tail call for MSVC for whats new in 3.15 (GH-143087)
---

diff --git a/Doc/whatsnew/3.15.rst b/Doc/whatsnew/3.15.rst
index 3c7e28a00c9c..aa138c9cacb0 100644
--- a/Doc/whatsnew/3.15.rst
+++ b/Doc/whatsnew/3.15.rst
@@ -849,6 +849,16 @@ zlib
 Optimizations
 =============
 
+* Builds using Visual Studio 2026 (MSVC 18) may now use the new
+  :ref:`tail-calling interpreter <whatsnew314-tail-call-interpreter>`.
+  Results on an early experimental MSVC compiler reported roughly 15% speedup
+  on the geometric mean of pyperformance on Windows x86-64 over
+  the switch-case interpreter. We have
+  observed speedups ranging from 15% for large pure-Python libraries
+  to 40% for long-running small pure-Python scripts on Windows.
+  (Contributed by Chris Eibl, Ken Jin, and Brandt Bucher in :gh:`143068`.
+  Special thanks to the MSVC team including Hulon Jenkins.)
+
 csv
 ---