Booster & Cleaner - Keeps fast significantly improves your device's performance by boosting its speed, deleting junk files, and clearing memory. It offers an app manager for organizing your apps as well as a whitelist feature for accessing your frequently used applications. Moreover, this tool has a battery status viewer for checking your phone's remaining battery life. 

Under “Battery Management,” you can toggle “Long Standby Mode,” “Sleep Mode,” or “Normal Mode.” Requiring only Android 4.4 and up, Booster & Cleaner - Keeps fast works with most older phone models for increased accessibility. It's lightweight and doesn't consume a lot of your phone's storage.