Here are some suggestions that can improve your performance
First of all, restart your device. It solves a lot of issues. Your phone will work better if you restart it once per week.
Second, go to system settings -> battery -> powermaster -> auto-start manager and prevent all the apps to auto start that you don't need a notification from.
After this go to system settings -> advanced -> Mobile Manager -> Memory cleaner -> Turn on Super Clean mode -> enter app list and uncheck any app that you must get notifications from -> go back -> open recent apps overview and press clear all.
Restart your phone.
In Armoury Crate, go to scenario profile for your game
In network, it is recommended to prevent the automatic switching of the network connection. It is known that automatic switching may cause disconnection during gameplay. It is also recommended to turn off background system synchronization to avoid automatic synchronization taking up network resources.
In the Performance section, set the [Temperature control] slider to [High]. Enabling [Memory Cleaner] is also recommended.
If none of the above helps, then reinstall your game, restart your device and redo all the armory crate settings. Hopefully this will fix it!