The Air 1 is an underpowered device and Apple is totally ignoring it. It's funny that they are because it performs about the same as an iPhone 6 Plus, which has been one of their flagships for the past year. The switcher is mostly smooth for me on my mini 2, it's just entering and exiting the switcher or closing apps that is bad. Oh and for some reason, simply scrolling past the home screen causes stutter, but everywhere else is okay. Everything else performance wise is similar to iOS 8, so I can't complain too much. I actually have reached the point where I am using grayscale wallpapers so I can always have increase contrast on without the hideous dock or folders being too noticeable because I'm sick of the stuttering. I wish I could just use my iPad like this for the rest of its lifetime but I probably wont be able to bare it, still looks kind of ugly.