Re: Display slowness that is painful

[Kim F. Storm]

"Richard M. Stallman" <address@hidden> writes:

> Thanks for writing that optimization.  I figured some such simple fix
> would be possible.  Please install your fix.
>
> What my experience has taught me is that cases of anomalous gross
> slowness often have a simple fix.  Thus, before taking up the
> difficult question of whether major surgery is justified, it's a good
> idea to look for a fix like this one which does the job with a band-aid.
>
> (Yi-dong found a different way to apply a band-aid, but it assumes
> that the file was visited in Image mode, so it doesn't solve the whole
> problem.  This change does, I think.)


While debugging this, I noticed that sometimes redisplay was (quite) fast,
while at other times, it was VERY slow.

I traced this to emacs starting to process SELECTION_REQUEST_EVENT
events after each redisplay round -- and consequently doing another
redisplay...  So in effect it never seemed to reach a point where it
would actually update the display.

Doing M-: (setq redisplay-dont-pause t) RET made redisplay much
snappier in this specific case.

Perhaps we should have some form of timer associated with the
(default) redisplay-dont-pause == nil case, so that even if
input_pending, we will still update the display if the last completed
redisplay happened more than, say 2 seconds ago.

-- 
Kim F. Storm <address@hidden> http://www.cua.dk