Re: Long lines and bidi

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sat, 09 Feb 2013 12:01:46 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: dmantipov@yandex.ru, emacs-devel@gnu.org
> 
> That is why I think we should attack this problem one reason at a
> time.  The most important reason is the first one: long lines cause
> the display code traverse too much of buffer text.  This is why you
> see x_produce_glyphs so high on the profile in the unidirectional
> case: it examines too many characters, much more than what will be
> actually displayed on the screen.

I just committed to the trunk revision 111724 with a couple of simple
changes which speed up by a factor of 3 some redisplay operations,
such as M-v or M->, in a buffer with very long lines.  Please try it.

This is by no means the complete solution, even for the situations
where it provides a 3-fold speed-up: we need the speed-up to be much
more aggressive.  But it does demonstrate how simple changes can have
a significant effect in this area.

Stay tuned.