They're trying to waste it less. For example, it's now very common for me to see it simply not update when I move a window that's behind another window. Which kinda ruins part of the magic for me.
Tahoe can't ramp up the GPU frequency fast enough, and many animation like the QuickLook one often run at less than 30 fps. So much fun.
I've been there. When Compiz on Linux was all the rage. I grew out of it in like 2-3 months and turned everything off. The problem is with Apple you don't get to turn it off.