Re: Making font-lock handle long lines better

[Eli Zaretskii]

> From: Ryan B <address@hidden>
> Date: Fri, 10 Feb 2017 07:44:15 -0800
> 
> hi all! it seems like it's been a known issue for a while that font-lock is 
> slow on very long lines. i've tried lots of
> optimizations - jit-lock/lazy-lock, font-lock-maximum-decoration, etc. - but 
> even on modern hardware,
> fontifying still hangs my emacs for 5-10s on long lines, e.g. 10k-20k 
> characters, whenever they appear. 
> 
> i'm thinking of adding an opt-in line length limit to font-lock-mode, after 
> which it would stop fontifying, evaluating
> regexps, etc. within each line. i'd love to hear opinions on whether that 
> makes sense, and whether you might
> consider accepting it into trunk.

Please file a bug report by sending this information using
report-emacs-bug.  If you can attach to your report a minimal test
case that exhibits the problematic behavior, it will be appreciated.

Thanks.