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

[Eli Zaretskii]

> Date: Sun, 7 Aug 2022 20:53:58 +0300
> Cc: gregory@heytings.org, emacs-devel@gnu.org
> From: Dmitry Gutov <dgutov@yandex.ru>
> 
> 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.

It takes 0.5 sec here.