iOS 9 Performance Rate

[George Waseem]

iPhones (best to worst)
1. iPhone 6S / Plus
2. iPhone 5 / 5C
3. iPhone 5S / 6 / 6 Plus
4. iPhone 4S

iPad (best to worst)
1. iPad Air 2 / mini 4
2. iPad mini 3 / mini 1
3. iPad 4 / Air / mini 2
4. iPad 3 / 2

Basically, iOS 9 is wonderful on new devices and some old devices. Middle aged devices perform a bit better than iOS 8 but need a lot of improvement in comparison to older and newer devices.