iPhone 4s is the oldest device supported iOS 9, although Apple lets iPhone 4s supports the latest systems, but users still complain that the system runs slowly, the operation is not smooth, all this is actually due to the iPhone 4s hardware has lagged behind, while iOS is increasingly large.
Whenever a new system (or beta) released, EverythingApplePro always bring the latest system test speed comparison video for us in the YouTube channel. Recently, in order to test the different manifestations of iPhone 4s in different systems (iOS 5-iOS 9), EverythingApplePro brought a speed comparison video that five iPhone 4s respectively running different versions of iOS, we take a look. In order to compare the performance of each system, the video also uses a slow motion replay to let you see more clearly.
We can see from the video, the overall performance of iOS 5 and iOS 6 are better than iOS 8 and iOS 9. But if you want to experience the latest system, then, iOS 9 is the only choice, but with a not smooth experience.