They were running great for betas. People here expected major improvements for the GM.
Exactly. The betas were stable, but I did notice animation lags (and I reported it), but whenever anyone complained about a little lag here and there, people just said "Well, it's a beta… it will be optimized before release. Plus, there's debug stuff running in the background that only gets disabled in the GM, so the GM will perform better"
Well, here's the GM and it's the same as PB3 (to me).
System-wide metal was supposed to make animations smoother, but it actually did the opposite. I'm disappointed that they advertised performance improvements, but actually made it perform worse than 8.4.1.
The other thing that I've noticed (and others have pointed out) is that now you have to wait for the entire home screen animation to end (when hitting the home button) before you can tap on another icon, but in 8.4.1, you could tap an icon while the app was still closing and it would open immediately.