Re: Things got very slow: profiler output

[William Denton <william@williamdenton.org>]

On Thursday, March 7th, 2024 at 11:12, William Denton <william@williamdenton.org> wrote:

> I recompiled Emacs and Org last night and closed all my buffers except for two medium-sized ones, neither with any LaTeX in them. I restarted and spent a minute or two with one buffer, closing and expanding headings, and just moving around without typing, and it quickly slowed down. When I did do a bit of typing it was very laggy (and will only get worse). The profiler said this:
> 
> 44032 66% - redisplay_internal (C function)
> 42619 63% - jit-lock-function
> 42603 63% - jit-lock-fontify-now
> 42551 63% - jit-lock--run-functions
> 42547 63% - run-hook-wrapped
> 42543 63% - #<compiled 0x1badbc188025c93f>
> 
> 42535 63% - font-lock-fontify-region
> 42531 63% - font-lock-default-fontify-region
> 41987 62% - font-lock-fontify-keywords-region
> 40255 60% - org-do-latex-and-related
> 40243 60% re-search-forward
> 12 0% org-string-nw-p
> 1224 1% + org-activate-folds
> 156 0% re-search-forward
> ...
> 
> I'm happy to try anything else ...

I spent a while with git bisect this afternoon and the problem (for me) started here:

commit 5d186b499dde97f59a91dc11f4c4a15113d29f4d
Author: Ihor Radchenko <yantar92@posteo.net>
Date:   Sun Feb 25 11:42:44 2024 +0300

    org-fold: Refactor fontifying newlines after folds

That seems to fit with some of what the profiling showed, in that it's about font-locking, though why LaTeX is mentioned is beyond me.  When I was going through the bisect process I wasn't testing on files with LaTeX, I was expanding and folding some I regularly use that have some code blocks and tables with a few hundred lines.

My Lisp isn't good enough to see why this commit might have changed behaviour.  A couple of people had slowness caused by a spell-checker that was easily fixed ... has no one else seen a problem dating back to late February?  Ihor, does this suggest anything to you?  Is there anything else I could try?

Bill

--
William Denton
https://www.miskatonic.org/
Librarian, artist and licensed private investigator.
Toronto, Canada