https://thenextweb.com/apple/2018/06/04/ios-12-is-all-about-speed-and-performance/

At today’s WWDC, Apple revealed new details about the upcoming iOS 12, with particular focus on how it will improve speed and performance — even on some of Apple’s oldest devices.

Craig Federighi, Apple’s senior vice president of software engineering, took to the stage to introduce iOS 12. According to him, the update dramatically improves the load times of software. When devices detect you need a boost in performance, such as when launching an app, it will ramp up CPU performance instantly to optimizer performance. When you no longer need it, the CPU ramps down in order to preserve battery life.