Re: Major modes using `widen' is a good, even essential, programming practice.

[Dmitry Gutov]

On 07.08.2022 20:23, Eli Zaretskii wrote:
> > What jit-lock/font-lock actually do at the moment is to widen, then use
> > syntax-ppss, i.e. in effect scan from BOB.
> Yes, and that's SLOOOWWWW!

It's not slow on files of reasonable size. E.g. even if we take xdisp.c 
(the file I've seen referred to in complaints on CC Mode's speed),

  (benchmark 1 '(save-excursion (parse-partial-sexp (point-min) 
(point-max))))

reports 20-50 ms on my machine. And that result is cached too.

So whatever perceived slowness is there, it most likely comes from other 
sources.