Don't get too excited! I have iPad mini 2 with iOS 8.3 public beta 2, and the performance might be slightly better, but it is still laggy. There are still choppy animations for keyboard pop-up when opening spotlight, changing orientation in spotlight, safari favourite menu scrolling lag, and occational lag when exiting apps. Apple didn't fix much animation glitch for iPads yet. I think we might have to wait till iOS 9.
Lets hope it comes in iOS 9....
I bought an iPad Mini 2, to upgrade my iPad tutorial business and honestly, iOS 8 is freaking glitchy and buggy...My iPad 2 glitches less (but has more jerkiness).