Subject: bug#64391: buffer narrowing slowdown regression in emacs 29

From: Eli Zaretskii <[email-masked]>
Date: Sat, 01 Jul 2023 15:08:36 +0300

> From: Mattias Engdegård <[email-masked]>
> Date: Sat, 1 Jul 2023 13:37:08 +0200
> Cc: [email-masked],
>  Gregory Heytings <[email-masked]>,
>  Eli Zaretskii <[email-masked]>
> 
> 1 juli 2023 kl. 06.59 skrev Andrew Cohen <[email-masked]>:
> 
> > Just for fun I simply commented it out (since the test code doesn't use
> > labeled restrictions) and ran the test code, and the problem disappears:
> 
> The attached patch combines narrow-to-region and internal--label-restriction into a single function, internal--narrow-to-region. (We could also add the label as an optional argument to narrow-to-region.)

It does more than that, so I'd appreciate a more detailed description
of the changes and their rationale.

Thanks.