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

[Eli Zaretskii <eliz@gnu.org>]

> Date: Fri, 29 Jul 2022 10:44:27 +0000
> From: Gregory Heytings <gregory@heytings.org>
> cc: gerd.moellmann@gmail.com, 56682@debbugs.gnu.org, larsi@gnus.org, 
>     monnier@iro.umontreal.ca
> 
> > Please always assume that I gave these aspects and your perspective due 
> > consideration before making my changes, and please never revert them 
> > without discussing first.
> 
> Okay, I'll keep that in mind in the future.

Thank you.

> > In this case, "arbitrarily large" contradicts the text that follows, 
> > which describes the circumstances where that might not be true.
> 
> I've carefully chosen the words of the title, and it doesn't contradict 
> what follows, as far as I understand.  It says "Emacs is now capable of 
> editing files with arbitrarily long lines", in which "capable" means that 
> it can do it, but will not always do it.  The circumstances that are 
> described in the text that follows tell the reader that the remaining 
> cases in which Emacs would choke on such files are outside of Emacs' 
> responsibility, they are the responsibility of major and minor mode 
> writers.

The usual interpretation of "capable" in Emacs is that we do it unless
the user tells us not to.  Otherwise users will ask why not do it
whenever possible, definitely for a feature like this one.  So that is
the contradiction which I had in mind.