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

[Eli Zaretskii]

> From: Stephen Berman <stephen.berman@gmx.net>
> Cc: Gregory Heytings <gregory@heytings.org>,  56682@debbugs.gnu.org,
>   monnier@iro.umontreal.ca,  dgutov@yandex.ru
> Date: Wed, 10 Aug 2022 13:59:45 +0200
> 
> >                        These are the only brackets I could spot in the
> > file that enclose very large portions of text.  If removing them
> > doesn't help much, the only possible reason is that there are a lot of
> > bracketed stuff in this file.
> 
> I suppose so, though I guess this is a pretty typical one-line JSON
> file.

I think it's quite unique in that its bracketed segments are very
long.