I'm not understanding the relation between the gpu and the growing number of workspaces.
Have you installed or used any configuration programs, such as MyUnity, or compizconfig-settings-manager?
Let's also make clear that this is indeed default Ubuntu 12.04
As always a screenshot is worth a lot of time.Code:echo $DESKTOP_SESSION
(Hit the prntscrn button to capture an image.
It'll be saved in the Pictures folder)