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

[Eli Zaretskii]

> Date: Thu, 2 Sep 2021 21:08:18 +0000
> From: Alan Mackenzie <acm@muc.de>
> Cc: emacs-devel@gnu.org
> 
> Hello, Stefan.

I'm not him.

> +           ;; The first function in `jit-lock-functions' can expand
> +           ;; the region in `tight-beg' and `tight-end'.  This
> +           ;; expanded region is passed to the subsequent functions.
> +           ;; The union of all the regions the functions mark for
> +           ;; fontification is stored in `loose-beg' and `loose-end'.

The "union" part is not clear enough, and should IMO be explained.

More importantly, this cannot hide in a comment, it must be clearly
documented, both in doc strings and in the ELisp manual.  (Assuming
this is the change we will go with, of course.)