Re: Long delay after M-x commandname

[Eli Zaretskii]

> Date: Mon, 11 Oct 2021 00:03:19 -0400
> From:  Stefan Monnier via Users list for the GNU Emacs text editor 
> <help-gnu-emacs@gnu.org>
> 
> Eduardo Ochs [2021-10-10 21:45:39] wrote:
> 
> > Yesterday I noticed that when I was invoking commands with M-x
> > commandname and using tab for completing parts of the name then
> > sometimes there would be a long delay - sometimes as long as 10
> > seconds, but my laptop is quite old - between the RET and the
> > execution of the command. This delay was big on emacs28 and
> > practically imperceptible on emacs27. I have several versions of
> > emacs28 here, with names like emacs28_512 for the one correponding to
> > HEAD~512 and emacs28_0 for HEAD, and I noticed that this delay was
> > growing in recent versions: small in HEAD~256, bigger in HEAD~128,
> > much bigger in HEAD~0.
> >
> > I _guess_ that these delays are caused by the code that generates
> > messages like this one:
> >
> >   You can run the command `find-eev-install-intro' with `M-x f--i-i'.
> 
> This message can be suppressed with `extended-command-suggest-shorter`.
> 
> It can take work to find that shortest replacement (it's a kind of
> brute-force algorithm which tries all combinations of increasing length
> until one works), indeed, tho usually it's negligible.  I'm surprised
> the time taken has changed significantly recently  That code has been
> the same Emacs-26, AFAIK.  The completion data has an impact on the
> performance, so maybe that's what's going on, but it still seems
> surprising you'd see such a progressive slowdown.

FWIW, I don't see any delay in "emacs -Q", so I think the question
becomes what kind of customizations and packages loaded could
significantly increase that time.