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

[Lin Sun]

On Fri, Nov 1, 2024 at 7:58 PM Eli Zaretskii <eliz@gnu.org> wrote:
>
> I'd like us first to have a good understanding of the problems, their
> aspects, and the goals of the proposed changes.  I'd also would like
> to have some agreed-upon timing of searching load-path, including its
> dependence on the number of directories in load-path, and the relative
> part of the startup that this particular aspect explains.  (Are you
> really saying that it takes Emacs 16 sec to search 300 directories for
> 300 files?)  Only then we will have enough information to discuss
> potential solutions and their effects on the startup time.

I use Spacemacs which will install ~380 packages for emacs. And on
windows without my patch, it takes ~16 seconds on startup, takes more
than 3 seconds to open a *.org file; as a comparison, similar
configuration on Ubuntu, the startup time is less than 4 seconds, and
takes less than 1 second to open a *.org file.

After applying the "load-hints" patch, on Windows the startup time is
reduced from ~16 seconds to ~5 seconds, taking ~1.5 seconds to open a
*.org file.  It does not imply Emacs spends 16sec to search
directories for 300 files on windows.

> In general, a Windows-only feature is something I'd prefer not to
> have, because quite a few users use Emacs on both Windows and
> GNU/Linux, so having OS specific features should be avoided.  But it
> can be acceptable if no better alternative exists.  But this is
> something we should talk about much later, not now.

Totally agree, really look forward to an elegant solution.