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: Fri, 19 Aug 2022 18:16:52 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> Could the reason you're not seeing this be because flyspell-mode doesn't
> >> trigger for you?
> >
> > What do you mean by "does not trigger"?
> 
> That flyspell-mode doesn't work.

It does work.

> Eval this:
> 
> (progn
>   (pop-to-buffer "foo.txt")
>   (flyspell-mode)
>   (insert (propertize (make-string 20000 ?x) 'display "foo")
>         "\n\n"))
>  
> Then type "d".  [Narrow] is shown in the mode line.

I types "s".  Does it matter what you type?