bug#68249: 30.0.50; Rmail summaries much slower

[Eli Zaretskii]

> From: Richard Stallman <rms@gnu.org>
> Date: Thu, 04 Jan 2024 23:23:37 -0500
> 
> 
> In master from Jan 1, making Rmail summaries has become far
> slower than it was on July 2.  I am calling rmail-summary-by-topic
> and have around 7000 messages in the RMAIL file.  It takes many secnds
> to finish, now.
> 
> Can anyone suggest a way to investigate the cause of the slowdown?

Before invoking rmail-summary-by-topic, type

  M-x profiler-start RET RET

Then, after rmail-summary-by-topic finishes, type

  M-x profiler-report RET

In the buffer presented by the last command, type "C-u RET" on every
line that has a "+" before it, to fully expand the profile.  Then look
at the profile to find the hot spots.

The profile is more detailed if you load rmailsum.el, not
rmailsum.elc.