Games : Massive FPS Drop in Minecraft when I try to record with OBS

So when I play Minecraft I set the FPS to 60FPS max so I don't get any frame tethering and I'm always on 59/60FPS unless like a nuke goes off or something then I drop down a bit... I use OBS to record and normally I have no problems yesterday I was recording staying at 59/60FPS the whole time while roaming the world. Today I try to record and I drop to 22/23FPS when I hit record on fullscreen or windowed mode. I don't have the best PC but its decent and because I thought OBS uses a bit of CPU power I got a FX-6300, GPU: Radeon 6870 and 8GB RAM @1600MHz.

I've had this problem once before so I just restarted OBS and it worked fine but today its not changing anything...

Any help would be greatly appreciated.