Re: lazy-lock vs. jit-lock

[Eli Zaretskii]

> Date: Thu, 29 Dec 2005 13:20:11 -0500
> From: Ian Zimmerman <nobrowser@gmail.com>
> Cc: help-gnu-emacs@gnu.org
> 
> > Lazy-lock has some known bugs (I remember some missing on-screen
> > fontification using outline-minor-mode, for example), >is less efficient<
> 
> Can you expand on the last point?  What makes lazy-lock less efficient?

It is less efficient because it uses ad-hoc mechanisms to detect when
the screen contents has changed (and therefore it's time to maybe
fontify the part that wasn't displayed before).  JIT Lock was written
to take advantage of special redisplay hooks that were introduced in
Emacs 21, so it never has to guess whether portions of the screen were
redrawn.  (By contrast, lazy-lock existed before Emacs 21, and needed
to live without such redisplay hooks.)