bug#71644: 30.0.50; Severe slowdown in larger files with markers beginning in emacs 29+

[Eli Zaretskii]

> Cc: 71644@debbugs.gnu.org
> From: Ihor Radchenko <yantar92@posteo.net>
> Date: Sat, 22 Jun 2024 13:53:08 +0000
> 
> Mitchell <mitchellahren@gmail.com> writes:
> 
> > Here are the steps to reproduce the issue:
> > ...
> 
> For the record, I am able to reproduce the problem using the latest
> Emacs master.
> 
> And the problem does disappear with my patch that affects the marker
> loop in src/marker.c (buf_bytepos_to_charpos)
> 
> So, markers appear to be the culprit on my system.

Not the markers, but conversion of character positions to buffer
positions.  Which uses markers, but that's an implementation detail...