Android (rooted): Your Android phone launches a number of applications and services in the background when you start it up. You can keep unwieldy battery and performance hogs at bay with BootManager for Xposed.
This module shows you everything that is scheduled to run at startup. It should be noted that some things can be necessary without being obvious, so if you're not sure what you're playing with, proceed with caution. That being said, you can help make sure that certain services only launch once you need them (looking at you, Facebook), rather than draining the battery from the word go.