I continually see posts about iOS performance for older devices and even current ones being lackluster in iOS 11 beta. These people keep hoping to see a difference in the GM and while they probably will improve performance alittle further. However you won't see final performance until July next year when iOS 11.2.3 or 11.3.1 or whatever is released. Apple does this every year, why set yourself up for disappointment in the GM or even official release when we all know it'll take months before iOS 11 is truly "polished"