bug#57207: 29.0.50; Fontification is slow after e7b5912b23 (Improvements to long lines handling)

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: 57207@debbugs.gnu.org,  yantar92@gmail.com
> Date: Sat, 20 Aug 2022 11:15:51 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Ah, I know what's causing this: flyspell calls redisplay (via sit-for)
> > inside its post-command-hook.
> >
> > So I think this basically means we cannot narrow the buffer while
> > calling pre- and post-command-hooks, because any of them can trigger
> > redisplay, and that will show "Narrow" on the mode line.
> 
> Would binding `inhibit-redisplay' there help?

Maybe it will, but how can we do that?  It would break any pre- and
post-command hooks that do need to trigger redisplay.