Sooner or later, your Android phone will slow down. No matter how high your phone quality is, your phone performance would be slowed down if there are many bugs and lags on your phone system. Bugs and lags could be happen because of several reasons. The first reasons is the app that you installed on your phone. Some apps have many services that need to be runned when the apps are installed. The service would eat the RAM memory. The second reasons is cache. Certain app need to keep data. The data saved by the app is called cache. The bigger the cache is, the lower the internal memory would be. Thus, there are several useful app to help you to speed up you Android phone again.
The first app is an auto task killer. For older phone, this app is very useful. The recent apps can run in background process automatically. This app would slow down your Android phone performance. This the auto task killer will kill certain application every time (seconds or minutes). You can choose which apps that should be killed the background process. As a result, the RAM memory would be free again from unused background app process.
The second app is an antivirus app. This app can help you to find any possible malwares and viruses inside the Android system. The viruses and malwares are also slowing down your phone. Thus, the antivirus app can help you to speed up your Android phone. But remember, most of antivirus app need large space. Make sure your phone has sufficient internal memory space to install the antivirus app.
The last app is a cache cleaner. This app would clean all cache created by apps on your phone. It can be set to be automatic as well so that the app can erase the cache regularly.