New launcher causes game to run at very low FPS

This bug is not triggered by anything in-game or by clicking anything in the launcher. Launching MC with this 'new and improved' launcher causes the problem. The problem is that when playing, you get much lower FPS than you normally would if you would have launched it with the old launcher. I normally get 60 fps with the old one. now I get anywhere between 8-30 fps with the new one.