Premiere Pro bugs

I have been facing a lot of bugs and technical issues from PR
1. Half of the windows are lagging and blackout, I have tried restart, make more RAM. If will be back to normal for a few secs when I press F1 or exit. 
2. The playback monitor is lagging, it will be back to normal once I switch the GPU processing thing. But after few minuties the problems comeback. 

HELPPPPPP!