Apple iOS 8 vs the first iPhone: here's why iOS feels clumsier now (video)

The thing is, however, that while the animations got flashier, the user experience suffered, as they got longer, and your input isn't detected while the transitional animation is running. This makes the whole interaction with the iPhone's interface appear slower than before, leading to numerous user complaints that iOS 7 and iOS 8 feel cludgy compared to previous iterations.

A user experience expert - William Van Hecke - recorded this phenomenon in the video below, showcasing how much slower iOS 8 is compared to iOS running on the original iPhone, for instance. While his explanation is that the animations aren't interruptible now, this has always been the case, it's just that those animations take longer to finish, so nimble-fingered users might run out of interaction patience, thus bringing the iOS 8 adoption rate to record slow rates. Apple has apparently taken notice, too, as it is rumored to focus predominantly on speed, stability and performance clean-up under the hood in iOS 9, rather than adding new features.