The app Geekbench provides a comprehensive set of benchmarks engineered to quickly and accurately measure processor and memory performance. Designed to make benchmarks easy to run and easy to understand, Geekbench takes the guesswork out of producing robust and reliable benchmark results. 

This app is used in a lot of YouTube videos when it’s most of the time ran when a YouTuber does a new device unboxing. What this does is measures the processor and memory performance of the device. This app is normally .99¢ but right now it’s free! So I would advise you get to the AppStore and get your free copy now!