FPS drop plus UI disappearance

I have this issue (tends to happen in Dalaran and while flying in Northrend- worst offenders are Dragonblight/Crystalsong Forest) where my fps will fall to 1 or so, and sometimes when I adjust the camera angle the entire UI dissappears and sometimes the whole screen goes black (although I'm clearly logged in and actions can be taken, I can tell from the sounds). The fps will remain terrible (less than 15) and the UI/screen will dissappear and reappear as I adjust the angle of the camera. Basically the only way to fix this is a full reboot of the game. Obviously I can live with it, but it gets extremely annoying and figured I'd post it here to see if anyone else has had similar issues in the past and if they had any solutions. Computer is fast, modern, etc- no potato here.

You may try applying this to WoW.exe: https://www.techpowerup.com/forums/t...-aware.112556/ to make it a bit more stable.
As for the screen issues, not sure what could cause that. Perhaps an addon?