Subject: bug#40611: Fontification of source bufffer can make Occur very slow (Emacs 27.0.90 pretest)

From: Lars Ingebrigtsen <[email-masked]>
Date: Mon, 26 Oct 2020 12:43:40 +0100

Konrad Podczeck <[email-masked]> writes:

> Open a latex file for which "M-x occur Ret the Ret" gives about 3000
> hits. If the source buffer is fontified, it takes about 2 seconds
> until the occur-buffer pops up, a time that is about 7 times longer
> than starting the Emacs app! On the other hand, without fontification
> of the source buffer, the occur buffer pops up almost
> immediately. Setting the user option "occur-mode-hook" to nil has no
> effect on this difference.

I tried this in a tex file with about 2700 "the" matches, and it took
about half a second whether font-lock-mode was on or not (I assume
that's what you mean by "without fontification").

So I'm unable to reproduce this problem.  Are you still seeing this in
newer versions of Emacs?  If so, do you have a test file that
demonstrates this problem (starting from "emacs -Q")?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no