Re: Low redisplay performance (23 regression)

[David Reitter]

On Apr 29, 2009, at 1:40 PM, Tassilo Horn wrote:
> And on yet another related note, today I've found out that after
> changing the font scale for the current buffer using `C-x C-+' or `C-x
> C--' line-by-line scrolling slows down considerably.

As said earlier, I found that using face-remapping is highly  
correlated with this slow-down.

> Oh, yet another observation: While writing this mail I enlarged the  
> text
> scale with `C-x C-+' and if I press and hold the up or down key, point
> hangs for very short periods of time at some positions and then jumps
> over some lines without visible redisplay, even though no scrolling at
> all is done.

I see the same thing.  Did you (setq redisplay-dont-pause t) ?
Either way, it suggests that drawing takes much longer with a change  
of faces. (E.g., M-x list-faces-display ?)