They aren't optimising anything.8.4.1 WAS PERECT on my 6 because it was optimised for 1GB devices.Hence the Air 2 handled the OS like a boss back then.With iOS 9 these stutters rear their ugly head every now and thenApple in general does optimize it's code toward the end of a release cycle. These stutters are silly programming(errors) in random places, why would the cellular screen stutter in settings?
Plenty of people go back and forth. It's different with desktop class hardware where top end video cards expensive, buying a $600 amd card after nvidia is not easy.
Lol.Its a universal fact that the walled garden approach of Apple makes it terribly difficult to migrate to any other OS.iMessage is a nightmare to migrate.I can't even wirelessly send photos from my iPhone to android like I can with another iPhone without resorting to the cloud.For those who got the Watch they are stuck in iOS like in a quicksand as you can't upgrade both at the same time unless you spend $1000+ at the same time so you will need to do without a watch for the interval