I installed the new OS on both my ipad 4 and the iPhone 5. Didn't do a clean install. The performance difference is night and day. On the iPhone 5 it is smooth as silk, totally fluid. On the ipad 4, it is jittery and feels like a beta release. I feel that if I did not have the iphone 5 to compare with, I probably wouldn't have noticed the relative "slowness" on the ipad 4. I originally bought the ipad 3 when it came out but was lucky enough to sell it at almost cost when the ipad 4 was announced. I hope that when the ipad 5 is released that the 4 doesn't suddenly become the new stepchild because Apple decided to skip optimizing the iOS for it.