The situation with 10.6.4 is a little bit better but time after time the animations are sluggish/choppy. When i use my Macbook (unibody white late 09) in battery mode then the animations are extremely choppy. And the big joke is: Apple make the animations in the iphone OS (like the ipad) silky smooth but these devices have not the horsepower of a Mac and when i look at the Mac with all his capabilities then i´am asking myself why is Apple not able to fix this?
I don´t understand this and this is a disappointment to me.
While the Spaces animation looks just fine on my iMac I also experience the almost non-existing animation in Exposé (the windows just "jump" into their overview positions immediately).
Here's my system overview: iMac 27", Intel Core i5 (2.66 GHz), 4 GB RAM, ATI Radeon HD 4850 (512 MB RAM) running Mac OS X 10.6.4. I also see the faulty behaviour on the iMac in my office with other hardware specs.
Now, what seems to work for me (testing that solution for about 30 mins now):
Whenever I hide (using ⌘H) or quit iTunes my Exposé animation looks just fine — fast, but smooth.
When I minimize iTunes to the Dock (using ⌘M or double-clicking the window title).
Also when having opened the iTunes in "normal" mode (meaning it's just there on my desktop) the Exposé animation seems to be OK, too.
I will continue testing this on my office iMac tomorrow and keep you updated on the results. Perhaps someone else could try this solution as well.