[cmaloney]

• Look up file.write once per print() call, instead of once for each argument, separator and line ending.
• Pass the cached ' ' and '\n' strings for the default sep and end directly, instead of converting them from C strings with PyFile_WriteString(), which runs strlen() and the UTF-8 decoder on every call to get back the same cached string.

write() receives the same calls as before. Benchmarks are in the issue: 1.20x faster geometric mean across 8 cases, 5 faster (1.12x to 1.66x) and 3 not significant.

Developed with the help of AI: Claude Opus 5.5.

• Issue: Speed up print() by looking up file.write once per call #160725

[python-cla-bot]

All commit authors signed the Contributor License Agreement.

[cmaloney]

(force pushed to fixup author line and make cla bot happy)

[methane]

How about concatenating everything and making a single write() call instead of calling file.write() repeatedly? This would likely improve performance significantly. It would also prevent standard output from getting garbled when multiple threads call print(a, b), since another thread could otherwise call print() between the file.write(a) and file.write(b) calls.

[cmaloney]

I started with that but then found it didn't produce uniform speedup: Copying strings of various sizes into a PyUnicodeWriter instead of doing the "pending" list that TextIOWrapper does would slowdown for some string sizes. It also very significantly changes behavior if a __str__ implementation causes a fault / SIGSEGV. I then profiled and found the repeated method binding was actually most of the runtime so built this PR.

In the longer term I'm hoping to add what I call a "Coherent" print; everything in one print statement gets write() to the underlying device not interleaved with any other print statement. That is a couple versions away though: need to support list of buffers through a lot more of the stack.