I can't wait for iOS 9 to be released. Just downloaded and installed iOS 8.4 on my iPad Air and it stutters as before.
I'm really anxious to find out how iOS 9 is. Yes, it uses Metal for the animations, but even so, most everyone has said iOS 9 is no different with UI performance really, or if anything, it's worse. It still is too early to say anything, but I'm still willing to say that we really are only getting marginal improvements with iOS 9 if there's anything to be said at all.
Oh crap sorry for the double post, meant to hit edit on my last post instead of reply.