How to prevent apps and processes from launching in background and slowing my device
Naming Gavity box running on your device implicates it is rooted, so you could use the full powers of Greenify. Greenify "temporarily freezes" apps which are running in background (of course only those the user specified). Other than with "deactivating" or "freezing" apps using e.g. Titanium Backup, such apps stay available in all places (including the app-drawer) and, in most cases, even can receive notifications (GCM etc.). It's more "putting them to sleep" than "freezing them".

Greenify can be used on non-rooted devices as well, but its full powers are unleashed with root (and the donation package plus the corresponding Xposed-module). Definitely worth a look.