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

[Dmitry Gutov <dmitry@gutov.dev>]

On 20/07/2023 15:22, sbaugh@catern.com wrote:
>> I'm not sure we should bother more than these two simple measures.
> Unfortunately those two simple measures help rgrep but they don't help
> project-find-regexp (and others project.el commands using
> project--files-in-directory such as project-find-file), since those
> project commands pull their ignores from the version control system
> through vc (not grep-find-ignored-files), and then pass them to find.

That's only a problem when the default file listing logic is used (and 
we usually delegate to something like 'git ls-files' instead, when the 
vc-aware backend is used).

Anyway, some optimization could be useful there too. The extra 
difficulty, though, is that the entries in IGNORES already can come as 
wildcards. Can we merge several wildcards? Though I suppose if we use a 
regexp, we could construct an alternation anyway.

Another question it would be helpful to check, is whether the different 
versions of 'find' out there work fine with -regex instead of -name, and 
don't get slowed down simply because of that feature. The old built-in 
'find' on macOS, for example.