bug#41646: Startup in Windows is very slow when load-path contains many

[Eli Zaretskii <eliz@gnu.org>]

> From: Lin Sun <sunlin7.mail@gmail.com>
> Date: Sun, 13 Oct 2024 14:47:46 +0000
> Cc: Stefan Kangas <stefankangas@gmail.com>, acorallo@gnu.org, 41646@debbugs.gnu.org, 
> 	monnier@gnu.org
> 
> On Sun, Oct 13, 2024 at 10:43 AM Eli Zaretskii <eliz@gnu.org> wrote:
> >
> > > From: Stefan Kangas <stefankangas@gmail.com>
> > > Date: Sun, 13 Oct 2024 09:50:42 +0000
> > > Cc: Andrea Corallo <acorallo@gnu.org>, 41646@debbugs.gnu.org,
> > >       Stefan Monnier <monnier@gnu.org>
> > >
> > > Why should this be MS-Windows specific, BTW?  Is slow startup time with
> > > many packages much less of an issue on other operating systems?  Is disk
> > > access somehow slower on MS-Windows?
> >
> > I don't think this is Windows-specific, it's just that on Windows the
> > gains might be higher.  Disk access is somewhat slower on Windows,
> > yes.
> 
> Thanks, and append the result on Ubuntu: from 2.132 to 1.573seconds
> (383 packages).
> 
> 
> On Sun, Oct 13, 2024 at 9:50 AM Stefan Kangas <stefankangas@gmail.com> wrote:
> >
> > Here's a suggestion:
> >
> > Since this is about speeding up load time during startup, how about
> > adding a new defvar that enables a cache for `require`, and then set
> > that to t during startup and nil after?  That would make the feature
> > work as expected without any user customization.  In general, this is
> > preferable, as this reduces the overall complexity of Emacs, both for
> > users and developers.
> 
> The "loadhints-cache" is not only for startup, actually it also works
> anytime when requiring a feature but the `exec-path' has hundreds of
> entries.

Is it possible to extend filecache.el to cover this use case as well?
For example, by adding to filecache.el the ability to save the cache,
and perhaps also the ability to collect the cached files by hooking
into 'load'?