If you need to stretch out a device as long as possible you may sometimes find yourself using a slower device. As devices get older ram gets used up and your phone can slow to a molasses style crawl. There are a few apps out there that can help you clean up your phone to improve its speed. One of the most in depth speed booster apps has to be "DU Speed Booster".
This app also includes a built in Antivirus security feature. The DU speed booster speeds up your phone by up to 60%. It does this by cleaning up junk cache files, and can even free up some storage on your internal sd card. There is a smart-cleaner feature which allows you to set up automatic cleanups of unwanted processes and trash. Speed Accelerator diagnoses and accelerates your system with custom optimizations. There are way to many features to list here. For a full list of features head to the Play Link below.
via Play Store