Python 3.15's interpreter for Windows should be 15% faster

Re:Python 3.15's interpreter for Windows should be 15% faster by kenjin4096 on Thursday December 25, 2025 @09:33AM (#46384633)

Thanks for reading! For now, we maintain all 3 of the interpreters in CPython. We don't plan to remove the other interpreters anytime soon, probably never. If MSVC breaks the tail calling interpreter, we'll just go back to building and distributing the switch-case interpreter. Windows binaries will be slower again, but such is life :(.

Also the interpreter loop's dispatch is autogenerated and can be selected via configure flags. So there's almost no additional maintenance overhead. The main burden is the MSVC-specific changes we needed to get this working (amounting to a few hundred lines of code).

> Impact on debugging/profiling

I don't think there should be any, at least for Windows. Though I can't say for certain.

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Re:Python 3.15's interpreter for Windows should be 15% faster by mishrapravin441 on Thursday December 25, 2025 @09:36AM (#46384646)

That makes sense, thanks for the detailed clarification. Having the switch-case interpreter as a fallback and keeping the dispatch autogenerated definitely reduces the long-term risk.

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