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

[Eli Zaretskii]

> Cc: sbaugh@janestreet.com, yantar92@posteo.net, rms@gnu.org, dmitry@gutov.dev,
>  michael.albinus@gmx.de, 64735@debbugs.gnu.org
> Date: Sat, 22 Jul 2023 20:46:01 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> 
> > First my results:
> > 
> > (my-bench 100 "~/public_html" "")
> > (("built-in" . "Elapsed time: 1.140173s (0.389344s in 5 GCs)")
> >  ("with-find" . "Elapsed time: 0.643306s (0.305130s in 4 GCs)"))
> > 
> > (my-bench 10 "~/.local/src/linux" "")
> > (("built-in" . "Elapsed time: 2.402341s (0.937857s in 11 GCs)")
> >  ("with-find" . "Elapsed time: 1.544024s (0.827364s in 10 GCs)"))
> > 
> > (my-bench 100 "/ssh:catern.com:~/public_html" "")
> > (("built-in" . "Elapsed time: 36.494233s (6.450840s in 79 GCs)")
> >  ("with-find" . "Elapsed time: 4.619035s (1.133656s in 14 GCs)"))
> > 
> > 2x speedup on local files, and almost a 10x speedup for remote files.
> 
> Thanks, that's impressive.  But you omitted some of the features of
> directory-files-recursively, see below.

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)"))

D:/usr/archive is a directory with 372 subdirectories and more than
12000 files in all of them.  The disk is SSD, in case it matters, and
I measured this with a warm disk cache.

So I guess whether or not to use this depends on the underlying
system.

Btw, you should not assume that "-type l" will universally work: at
least on MS-Windows some ports of GNU Find will barf when they see it.