Have a High Sierra VM set up, but getting black boxes all over.

I got my VM to boot up, but on some specific apps, especially Safari, there are black boxes that appear on certain websites.
Album of several examples.
Chrome doesn't have these issues of black boxes, but in youtube videos, things like the bottom info bar phase all over. A (slightly) better way to describe it is it's like you're in a game GPU is crapping itself and textures are phasing and stretching all over. It's not as bad as I'm describing it, but it's annoying enough to make me want to fix this.