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

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: yantar92@gmail.com,  57207@debbugs.gnu.org
> Date: Fri, 19 Aug 2022 17:50:03 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Is it true that the call which makes the narrowing comes from
> > safe_run_hooks_maybe_narrowed in your case?  If so, can you step
> > through the code after the narrowing and try to figure out why isn't
> > narrowing undone after the hook function returns?
> 
> I'm not sure, but that function is being called when I hit a key, at least:

And when you step through safe_run_hooks_maybe_narrowed, are BEGV and
ZV values restored when it returns?