One solution is to change your phone’s “Window animation scale”, “Transition animation...

One solution is to change your phone’s “Window animation scale”, “Transition animation scale” and “Animator duration scale” from 1x to 0.5x. Granted, it won’t actually make your phone faster, but it will make it feel faster. Go to Settings > Developer options and scroll about two thirds of the way down the list to find the necessary options (you’ll need to have first enabled Developer Mode).