I've read a few prelim reports stating that there is noticeable lag with the new iOS.
Is 7 optimized for the new A7 processor? Does anyone know how it will run/does run on Iphone 5?
I'll hold off on downloading and installing if it's significantly slower than iOS 6. Thanks.
A lot of people are confusing the new slower transition animations as 'slowness' or 'lag'.
iOS 7 has a whole new set of animations and their transition speed is far slower than the transition animations in iOS 6. It's nothing to do with performance of the device, it's a stock and preset speed for all devices.
Where there are 'issues' is in the iPad builds which, even on the 4th Gen, see some stuttering of these transition animations in certain situations (pinch to return to the home screen, zooming in on a selected app on multitasking, rotating between portrait and landscape mode, etc).
At times they're not huge stutters (the pinch to home and zooming in on selected app on multitasking are most noticeable) but in comparison to iOS 6 it's very noticeable in day to day use. It's not that the iPad build is unstable, it's fine reliability wise and most transitions are smooth, but there are niggles which detract from the experience people are used to on iOS 6.
The iPhone builds are spot on, and for me it shows that Apple spent more time optimising and perfecting performance on the iPhone first and foremost.
I've DFU restored back to iOS 6 on my iPad but will be keeping iOS 7 on my iPhone 4S as it's smoother in terms of transition animations all over the OS. I find my 4S experience on iOS 7 better overall than it is on my iPad 4th Gen.
Some will notice these stutters, some won't ... and that's before I start on the woeful keyboard lag on iOS 7. The last letter of words being typed not being recognised and it seems to take far too long to move from upper to lower case when pressing shift.