Hello, I noticed my FPS is normally capping out around 32ish even at low settings. When I try and stream it starts maxing at 22, averaging 17, and dipping to 14. I've even tried streaming with my graphic settings turned all the way down and my fps without streaming never goes above 33.
i5-4690k
gtx 970
16gb ram
I've streamed more graphically intense games including Legion which much higher results.
I have the exact same hardware as you and easily cap at 60 fps vsynced in heavy fights.
Try reinstalling your gpu driver or resetting 3d settings. Something is very off.