Re: bug-reference-prog-mode slows down CC Mode's scrolling by ~7%

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: Eli Zaretskii <eliz@gnu.org>,  emacs-devel@gnu.org
> Date: Sat, 04 Sep 2021 12:06:44 -0400
> 
> > Maybe.  An advantage of a small chunk size is that fontifying a single
> > screen can be done with a maximum 499 bytes "inefficiency" off the end
> > of a screen.
> 
> [ Well, 499 plus the effect of increasing the specified region by
>   rounding it up to whole lines and things like that, of course ;-)  ]
> 
> > If we were to increase jit-lock-chunk-size to, say 2000, more of the
> > next screen would be getting fontified, perhaps wastefully.
> 
> Indeed, I was thinking of increasing it only to 1000.

To see the "waste" in single-windowful scrolls, we need a suitable
benchmark, which measures the time of each scroll separately.  It
would probably make sense to make it generate a random value of point,
then measure the time it takes to go there and display.