bug#12468: 24.2; emacs becomes increasingly sluggish

[Eli Zaretskii]

> Date: Tue, 18 Sep 2012 13:23:32 -0500
> From: Rodney Sparapani <rsparapa@mcw.edu>
> 
> I recently upgraded to 24.2 from 23.1 and I like 24.2 much better; great
> job fixing bugs and adding features!  However, I noticed that after
> working for 30 minutes or so; emacs becomes increasingly sluggish.  So,
> I decided to profile it.  I've never done profiling before.  But, this
> seemed like the perfect time to try it; I really would rather use
> 24.2!  The profiling is below.  The amount of time consumed by
> valid_image_p seems suspicious (the formatting is a little screwy so I'm
> attaching it too)...
> 
> Flat profile:
> 
> Each sample counts as 0.01 seconds.
>     %   cumulative   self              self     total
>    time   seconds   seconds    calls  ms/call  ms/call  name
>    81.64    476.19   476.19   448475     1.06     1.06  valid_image_p

I think this is a duplicate of 12463, see there for a patch that might
solve your problem as well.