Apple said that iOS 9 will bring performance improvements to all iOS devices, including older models that were slowed down by the iOS 8 update. However, when all said and done, it turned out that iOS 9 wasn’t able to dramatically increase overall speed, no matter how much optimization it underwent.
Various early tests showed last September the initial version of iOS 9 lagging behind the latest stable version of iOS 8. Since then, Apple released a slew of minor update, with the latest one significantly improving overall user experience on old devices such as the iPhone 4s and iPhone 5. More →