I think "perfectly" is a bit of a stretch.
iOS 7 definitely works a lot better on a 5s however I've never experienced any lag with iOS 7 on my 4s. It has been a solid OS for me and never gave me any issues. For a phone with specs from 2011, it's still doing a pretty good job.I think "perfectly" is a bit of a stretch.
I'll probably upgrade to iOS 8 because the performance damage was done with 7... I'm hoping it doesn't perform any worse than iOS 7 does, given that there isn't too much new stuff to slow it down. The new features are welcome.
That's definitely not true. It lags like a ****************. Scrolling through pages in the springboard and inside folders, entering and going out of folders and bringing up control center and notification center (specially at the lock screen) all have rough and delayed animations. Compared to an iPhone 5s or even an iPhone 5 it's night and day.