Your the one who doesn't have a clue. iOS has gone down the toilet since iOS 7. It lags, it crashes, its horrible on the eyes, and looks awful. iOS 6 and earlier versions ARE much superior than current versions in terms of fluidity and stability.
And many have noticed that through out the years. And I have personally observed this on the iPhone 4s, 5, 5S, 6, 6s, 7, and 8.
I can make iOS lag when scrolling in safari on cnet.com articles and its home page but thats a safari issue since it doesnt do it in the chrome browser on the iPad pro. That's the Apple of today....