Question / Help FPS Drops on OBS when ingame but not when im out of game

[Sjofus]

Hello there. Im kind of new to streaming and stuff. But here goes. When i'm not in the game, like tabbed out of it, obs says its 60 fps in the corner. But when i tab back into the game it goes down to 40-60 all the time

My PC:
GPU: MSI TWIN FROZOR GTX 970 4GB
CPU: AMD FX-8350 4.0Ghz Octa core
RAM: HyperX Fury Red 16GB