Comment 29 for bug 153205

I can confirm this as well, and the above fix did not work for me. As long as I don't have a full-screen window, my alt-tabs are quite zippy. I can even leave a full-screen window open on one workspace, and switch to another, and on that second workspace my alt-tabs are perfectly normal. But if I try to alt-tab on a workspace that has a full-screen window on it, it takes a good 2-3 seconds. It's really, really bad.

Any ideas for a work around?