Re: C-n is very slow in Font-Lock mode

[Eli Zaretskii]

> From: Richard Stallman <address@hidden>
> CC: address@hidden
> Date: Tue, 26 Apr 2005 06:05:41 -0400
> 
>     > It turns out that vertical-motion was fontifying all the text that
>     > it moved over.  That seems to be easy to fix.
> 
>     Did you try my suggestion of customizing jit-lock-defer-time?
> 
> No, because I want to fix this, not work around it.  vertical-motion
> is a cursor motion function.  It should not fontify anything.

As David pointed out, vertical-motion does that for a good reason:
fontification can well change the pixel size of the glyphs that Emacs
needs to display.

I think jit-lock-defer-time _is_ the way to avoid the slowness if you
are willing to see the text unfontified for a fraction of a second.
IIRC, Stefan introduced that option to provide functionality similar
to now-obsolete lazy-lock.