[munch117]

What you don't see in the logs are the experiments and branches that weren't pursued further because they didn't perform well enough.

Also: If you're going to prove that changes informed by performance measurements are absent from the commit logs, then you'll need to look in the logs for all the relevant places, which means also looking at I/O and bytes and allocator code.

[saagarjha]

Given that the performance is only affected by the size of that object header, the file I linked is all you'd need to see changes in. Look, the Python project is not picking their object sizes because it performs well on a quirk of Zen 3. End of story. I did performance work professionally in the past and now recreationally and this specific instance is 100% luck. This is not because I don't think the runtime people aren't smart or anything but this would be an insane thing to do on purpose.