in the same boat here, iOS 11 update for my older ipad has made it slow/buggy and significantly worse for my use case (browsing the web and watching netflix)
For example in IOS 10 to enable night mode was -> "Swipe up, tap" done. In iOS 11 it now requires 2 swipes, a long press then a tap. Also minimizes the app in focus requiring another tap to get back to it. Why?