Droid-Arena

This great little app allows you to back up not just your entire device but also specific apps and their app data. Titanium Backup is especially useful when you install a new ROM and don't feel like re installing each app you had previously.

You can also automatically schedule backups, move apps to the SD Card to make more room on the internal storage, and sync app data with DropBox or Google Drive. So if you lose your device, you can still get your apps back once you replace it.

          

 SetCpu is a great app for controlling your device's CPU and GPU speed. You can use this app in conjunction with custom ROMs, kernels, or even on it's own to do a little overclocking (to make the device perform better), undervolting (to make the battery last longer), or setting different profiles so the device utilizes its processor more efficiently. 

             

Greenify can help you increase your performance and battery life by identifying apps and tasks that are running in the background, and using up system resources for no reason. You can also use it to make sure these apps remain in hibernation when not in active use. Greenify also helps you recognize possible malware and remove it