So that particular issue isn't some sort of a constant or a given fact as far as it being present for those who update to iOS 11. Simply possible (as most things are essentially), which is basically what I mentioned originally. Seems like we are in agreement.iOS 12 is the exception, so far.
Battery life seems really awful on iOS 12, yet overall performance - at least on several iPhone 7s I have seen - is near the initial iOS version, which is a great achievement by Apple.
Specific app-related quirks like those previously stated are still possible and have been reported, though, which is what I'm saying.