Ken Jin <kenjin4...@gmail.com> added the comment:

> IIRC, Carl got a lot of benefit out of reordering the opcodes in the main 
> loop to put the most common ones at the top.  I don't know if that is still 
> relevant or whether computed gotos, when enabled, change that calculus.

AFAIK, on nix systems with PGO, the order doesn't matter. Brandt did some 
interesting research on this earlier 
https://github.com/faster-cpython/ideas/issues/96.

On Windows, it might be a different story. There are reports of up to 5% 
speedups in pyperformance just by moving LOAD_FAST and LOAD_GLOBAL out of the 
loop (to the top).  See the last few messages in 
https://bugs.python.org/issue45116. I've heard from some people that MSVC's PGO 
doesn't deal with gigantic switch-case statements very well, though I can't 
confirm the veracity of that info.

----------
nosy: +kj

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