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

[Eli Zaretskii]

> Date: Sun, 7 Aug 2022 21:27:21 +0300
> Cc: 56682@debbugs.gnu.org, gregory@heytings.org, monnier@iro.umontreal.ca
> From: Dmitry Gutov <dgutov@yandex.ru>
> 
> > feel free to push a feature branch with your proposed
> > changes, or even install them as optional features on master, and
> > let's compare the merits and demerits of each idea in practical use
> > cases and on a variety of systems.
> I will.

Thanks.