gh-143658: Use str.lower and replace to further improve performance of importlib.metadata.Prepared.normalized
#144083
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….metadata.Prepared.normalized Co-authored-by: Henry Schreiner <henryschreineriii@gmail.com>
hugovk
changed the title
str.lower and replace to further improve performance of importlib.metadata.Prepared.normalizedstr.lower and replace to further improve performance of importlib.metadata.Prepared.normalized
hauntsaninja
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Jan 20, 2026
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Follow on from #143660 which replaced
re.subwithstr.translate.@henryiii discovered that whilst that is an improvement on Python 3.10-3.11 and 3.14, the performance of
str.translateis much worse on Python 3.12 and 3.13, and can be worse than the originalre.sub.Further, his fix in pypa/packaging#1064 to replace
str.translatewithstr.lowerandstr.replacecalls is better than both the other options across all Python versions, to varying degrees.I benchmarked all three across all available Python Build Standalone versions from 3.10-3.15 on macOS:
I also benchmarked Windows and Ubuntu it's the same pattern.
Whilst the improvement isn't as large for CPython 3.15 as it is for libraries such as
packagingthat support a wide range of Pythons,importlib.metadatadoes have a backport, and I'll update python/importlib_metadata#529 once this is merged.str.translateto improve performance ofimportlib.metadata.Prepared.normalized#143658