I’ve been having the same experience with iOS 11. I often open the phone app to call someone I recently talked to, see their name at the top, click it to call them, only for the phone to call someone else. What’s happening is that someone else had called me in the meantime and iOS showed me the cached image of the screen but registered my touch on the “real”/live view of the screen. Safari does the same thing on both iOS and OSX when you swipe back and interact with the page, and I’m sad to be seeing that behavior leak elsewhere. Super frustrating.

Also, the amount of lag when loading basic apps has increased significantly with this update (I have an iPhone 6s).