Please describe the problem:
When compositing is enabled in Metacity, the Alt+Tab behavior is excessively slow (around half a second for just simple window switching, about the same to display the window switcher if I want to move around to another window other than the last one I used).

This is on NVIDIA hardware; compiz works pretty well on it, but I didn't want the overhead of all of its stuff.  I just wanted transparent terminals.  :-)

Steps to reproduce:
Enable compositing in metacity, and alt-tab to another window.

Actual results:
There is about a half-second delay in the window switcher's appearance and behavior.

Expected results:
The delay should not be noticeable, such as when compositing in metacity is not enabled.

Does this happen every time?
Yes.

Other information: