[Dapper] Slow workspace switching

[Phil Hagelberg]

Hi. I just upgraded to Dapper yesterday, and I've noticed a strange
issue. If I have an image on my desktop background, switching between
workspaces is accompanied with a couple seconds of delay. If I switch to
a solid color for my desktop background, it's back to normal.

Does anybody else have this problem? I am running two dapper machines,
and it only happens on one of them. It may be Xinerama-related since it
happens on my multihead desktop and not on my laptop.

-Phil Hagelberg