bug#17124: 24.3.50; Occasional Extremely Slow Redraws in OSX Emacs

[Eli Zaretskii]

> From: Eric Froemling <ericfroemling@gmail.com>
> Date: Thu, 27 Mar 2014 14:23:28 -0700
> 
> I've been using various OSX emacs builds from http://emacsformacosx.com
> for a few years now.  I'm on a 2012 Retina Macbook Pro 15".  Every so
> often when I am resizing the emacs frame or window I get a single
> extremely slow redraw.  Here's a screen-capture video I was able to 
> take of one just now as it was occurring:
> http://www.files.froemling.net/misc/SlowEmacs.mov

I cannot see that movie on my box.  Do you see delays between
characters on the same screen lines, or is the delay between screen
lines?

> I have not found a way to reliably reproduce these, though they happen
> somewhat regularly when I am working.  Please let me know if there's
> any other info I can provide or anything I can do on my end to help
> get to the bottom of this.

Try to look at the CPU load when this happens, in particular if more
than a single CPU core is busy (assuming you have a multi-core CPU).
If more than one core us busy, it probably means that more than one
thread is using the CPU (Emacs redisplay engine is single-threaded).