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

[Dmitry Gutov]

On 01.08.2022 15:12, Eli Zaretskii wrote:
> But the problem here is that it isn't "people shooting themselves in
> the foot", it's that "major modes shoot their users in the foot".
> IOW, the ones who shoot and the ones who get shot are not the same
> people.
>
> What do you want a user to do when he/she is faced with a mode which
> makes Emacs very slow?  Such a user cannot blame his/herself; in many
> cases the use doesn't even know enough to realize it's the major mode
> and its fontifications that are the culprit.

Just like we do in such cases where an Emacs feature is not optimized 
enough for a given use case: wait for the user to realize the situation 
can and should be improved, and file a bug report/feature request.