Description

pablogsal

opened on Nov 9, 2026

Issue body actions

-X perf makes Python code much slower. The perf trampoline is a PEP 523 hook, so specialized calls and generator resumes are disabled while it is active, and the trampoline evaluator keeps an extra native frame alive on every call.

Slowdown with -X perf on main (PGO + ThinLTO, Clang 21):

Benchmark	Slowdown
generators	+234%
generator_resumes	+72%
python_calls	+50%
scimark_lu	+42%
pyperformance (geometric mean)	+12%

Linked PRs

• gh-161676: Reduce perf trampoline overhead #161677

Activity

1. aisk

   added

   type-featureA feature request or enhancementA feature request or enhancement

   performancePerformance or resource usagePerformance or resource usage

   on Nov 9, 2026
2. pablogsal

   added a commit that references this issue on Nov 9, 2026

   pythongh-161676: Fix perf trampoline offset signedness and news path

   5afac8d
3. picnixz

   added

   interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)

   on Nov 9, 2026
4. pablogsal

   added 2 commits that reference this issue on Nov 9, 2026

   pythongh-161676: Let the perf trampoline evaluator tail-call the tram…

   bd91c37

   pythongh-161676: Keep specialized calls enabled under the perf trampo…

   88c2e1b

Issue actions