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

[Dmitry Gutov <dgutov@yandex.ru>]

On 13.08.2022 20:16, Gregory Heytings wrote:
> 
>>> As I just said to Dmitry: the same multi-second delays we saw in 
>>> smaller JSON files.  And those who have a slower CPU will see these 
>>> multi-second delays with smaller files.
>>
>> No exactly the same ones, though, since the previous tests we did were 
>> done with the older version of JSON support (not the current 
>> js-json-mode), with somewhat different performance characteristics.
>>
> 
> Okay, not "the same ones", but delays of the same order of magnitude 
> nonetheless.  We had that discussion a month ago, and concluded that 
> local fixes in every major (and minor) modes were not the way to go.  
> Having that discussion again does not seem fruitful.

Did you have that discussion with other people who have not authored a 
single major mode? That's ridiculous.

> You improved 
> js-mode and created json-mode, that's fine, but it doesn't change 
                       ^
                        js-json-mode

> anything to the way all other major (and minor) modes behave.

It showed specific pitfalls we can take care of in other major modes as 
well.