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

[Eli Zaretskii]

> Date: Sun, 7 Aug 2022 01:58:06 +0300
> Cc: gregory@heytings.org, 56682@debbugs.gnu.org, monnier@iro.umontreal.ca
> From: Dmitry Gutov <dgutov@yandex.ru>
> 
> >> Either way, I believe the change is at the right level of abstraction,
> >> and if it has bugs, they should be solvable without major redesign.
> > 
> > Alas, Mr. ShouldBe is not available for this project, and probably
> > won't be any time soon.
> 
> No need to mock my request for a proper reproduction scenario.

It isn't mockery.  My point is simple: we would like to solve this
issue in the best possible manner in Emacs 29.  Keeping talking about
what should and shouldn't be done doesn't advance us on that path.  If
you have practical ideas to solve this in a way different from what is
now on master, 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.  Then we can eventually make an
intelligent decision about the optimal mix of features we want to
have.  But as long as there's only one practical idea that works
reasonably well, it is going to win if only for lack of "competition",
because leaving the situation as it is in Emacs 28 is not an option
anymore.