why my samsung s7 freeze every 30 seconds?

A

AC Question

i have samsung s7 and everything was ok untill i install golauncher and when i try to install a theme my phone freeze.i restart the phone using start button and volume down buton.after that i noticed my phone freeze every 30 seconds and it stay freezed about 2-3 seconds and than is okay but when im scroling its annoying.then i do factory reset but that didnt solve the problem also i install a new firmware and still nothing.anyone happened this? please help