Lag/ sliders do not work correctly

Since i updated to pre-release 4, I've had a fps drop from around 150fps to 50fps and most of the time its down to 15fps. This is when I'm sitting ingame in my house doing nothing. 

I also only have 58fps when I'm in the main menu.

This is a significant framerate drop that just happened overnight and I haven't changed any settings.

The sliders in the options menu doesn't seem to be working alright for me. You can click on the sliders and it works but I can't click and drag them in video settings, accessibility settings and chat settings. They work fine in music and sounds.{}