After upgrading to Ubuntu Gnome 13.10 recently, I was struck by how much worse graphical performance was in the overview, and was greatly disappointed, as I've been using Gnome on 12.04 for a very long time now without difficulties.
On a hunch I re-enabled UXA for the Intel graphics chip in place of SNA, and the difference is night and day - pretty much on par with what it was before. This is using a Sandy Bridge i7-2670QM, HD 3000 cpu.
To do so:
sudo nano /usr/share/X11/xorg.conf.d/20-intel.confPaste in the following text (ctrl + shift + v):
Section "Device"Ctrl + X to exit and save, then reboot.
Identifier "Intel Graphics"
Option "AccelMethod" "uxa"
Edit: I've additionally found that after upgrading to Kernel 3.12.1 overview performance has increased again.