bug#64735: 29.0.92; find invocations are ~15x slower because of ignores

[Eli Zaretskii]

> Date: Sat, 16 Sep 2023 04:32:26 +0300
> Cc: luangruo@yahoo.com, sbaugh@janestreet.com, yantar92@posteo.net,
>  64735@debbugs.gnu.org
> From: Dmitry Gutov <dmitry@gutov.dev>
> 
> >> I wonder what scenario that might become apparent in. Launching many
> >> small processes at once? Can't think of a realistic test case.
> > 
> > One process suffices.  The effect might not be significant, but
> > slowdowns due to new features are generally considered regressions.
> 
> We'd need some objective way to evaluate this. Otherwise we'd just stop 
> at the prospect of slowing down some process somewhere by 9ns (never 
> mind speeding others up).

That could indeed happen, and did happen in other cases.  My personal
conclusion from similar situations is that it is impossible to tell in
advance what the reaction will be; we need to present the numbers and
see how the chips fall.