Subject: bug#56682: Fix the long lines font locking related slowdowns

From: Eli Zaretskii <[email-masked]>
Date: Sat, 23 Jul 2022 20:44:43 +0300

> From: Gerd Möllmann <[email-masked]>
> Cc: [email-masked],  [email-masked],  [email-masked],
>   [email-masked]
> Date: Sat, 23 Jul 2022 19:23:40 +0200
> 
> Eli Zaretskii <[email-masked]> writes:
> 
> >> Font-lock Scroll-bar Composition Output
> >> ------------------------------------------------------------
> >> on	  on	     on		 GCs: 14 Elapsed time: 7.276626 seconds
> >> on	  off	     on		 GCs: 1 Elapsed time: 5.363002 seconds
> >> on	  off	     off	 GCs: 1 Elapsed time: 3.967520 seconds
> >
> > Thanks.  How about now, after I installed the last change?
> 
> Font-lock Scroll-bar Composition Output
> ------------------------------------------------------------
> on	  on	     on		 GCs: 16 Elapsed time: 5.496764 seconds
> on	  off	     on		 GCs: 1 Elapsed time: 5.362916 seconds
> on	  off	     off	 GCs: 1 Elapsed time: 3.947306 seconds
> 
> That's with
> 280b8c96cc origin/feature/long-lines-and-font-locking Improve display of columns on mode-lin

Thanks.  So the scroll-bar effect is largely gone, and font-lock is
now just 25% slower than no-font-lock.  Which I think is reasonable,
given that there's a face change every 10 to 20 characters?