I've felt that when you're in an app, e.g. Safari, and you hit the Home button, there an inordinately long pause that takes place before anything happens. It's the same when you hit the Home button when the phone is locked/off. Takes just a bit too long for the screen to come on... I compared it to my iPad 2 running iOS 5, and the difference is pretty staggering. When in Safari in both the iPad 2 and the 4S, hitting the Home buttons on both devices simultaneously results in the iPad 2 almost fully through the close-Safari animation before the 4S even does anything. Is this an iOS 5 issue with the iPhone 4 as well?