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

[Eli Zaretskii]

> Cc: dmitry@gutov.dev, yantar92@posteo.net, michael.albinus@gmx.de, 
> rms@gnu.org,
>  64735@debbugs.gnu.org
> Date: Sat, 22 Jul 2023 21:31:14 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> 
> My results on MS-Windows are less encouraging:
> 
>   (my-bench 2 "d:/usr/archive" "")
>   (("built-in" . "Elapsed time: 1.250000s (0.093750s in 5 GCs)")
>    ("with-find" . "Elapsed time: 8.578125s (0.109375s in 7 GCs)"))

And here's from a GNU/Linux machine, which is probably not very fast:

  (my-bench 10 "/usr/lib" "")
  (("built-in" . "Elapsed time: 4.410613s (2.077311s in 56 GCs)")
   ("with-find" . "Elapsed time: 3.326954s (1.997251s in 54 GCs)"))

Faster, but not by a lot.

On this system /usr/lib has 18000 files in 1860 subdirectories.

Btw, the Find command with pipe to some other program, like wc,
finishes much faster, like 2 to 4 times faster than when it is run
from find-directory-files-recursively.  That's probably the slowdown
due to communications with async subprocesses in action.