Android build slows time after a while

Hey!

I have a problem that occurs on my Android phone when I play my game for while. After few stages the game fps starts to slow down until it becomes unplayable. Now strange thing was that when I stopped the game from app manager in my phone and relaunched it, the fps wasn't same as it is when I build and run the project from my computer, but FPS was half from it. I am tracking it via script because I have no profiler.

Before I get into deeper debugging with tools for android, do you have any idea where could this kind of behavior come from? When considering the fact that the game fps drop stays even when stopping and relaunching the game.