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

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: acm@muc.de,  emacs-devel@gnu.org
> Date: Sat, 11 Sep 2021 14:00:57 -0400
> 
> >>     Maybe a good way to see the waste is to measure the time for the
> >>     initial font-lock in an outline-mode buffer where the screen is
> >>     filled with single-line headers and everything else is hidden:
> >>     a whole chunk will be fontified for each line, so with a single
> >>     40-line screen you can expect to fontify 40 chunks (unless the
> >>     hidden text between lines is smaller than the chunk size, of
> >>     course).
> >
> > That's okay, but the thing is we do fontify invisible text, and 1500
> > characters could be easily 40 lines, so the probability of more than
> > that to be hidden is not large, except in unusual cases like reading
> > Lisp in Outline mode with all the code hidden.
> 
> Where, your "unusual" is my default

With all the code hidden? really?  Why have that in Emacs at all, if
you aren't editing its code?