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

[Eli Zaretskii]

> From: Michael Albinus <michael.albinus@gmx.de>
> Cc: yantar92@posteo.net,  dmitry@gutov.dev,  64735@debbugs.gnu.org,
>   sbaugh@janestreet.com
> Date: Fri, 21 Jul 2023 19:55:22 +0200
> 
> I'm open for any proposal in solving the performance problems. But since
> I'm living in the file name handler world for many years, I might not be
> the best source for new ideas.

The first idea that comes to mind is to reimplement
directory-files-recursively in C, modeled on how Find does that.