Try quickly typing 1+ 2 + 3 into the iOS 11 Calculator
I see so many people here saying that their performance in older iPhones has declined with iOS 11.I would like to point out that most (if not all) the lag issues and other performance related issues can be reproduced on a current iPhone 8. I have one. The flashlight has a noticeable delay when turning it on, the calculator is broken as described, the UI gets stuck a lot, apps crash a lot etc.This is not a money grabbing scheme by apple. iOS 11 is just really bad software. Not the calculator though, this problem is older and has been there in iOS 10 aswell.