Removing MVP since current perf is fine for launching. Chris, please re-add MVP if you disagree.

I completely agree.  Thanks Tibor!

Just a thought: What if we made the background renderer aware of where the holes for the quad layers need to be and it handled drawing transparent there? Would that be expensive?

If we were using the depth buffer, we could stuff the holes in there, but that seems to add to the specific problem we're trying to solve (we'd be drawing quads, then the background, then the quad layers).

In the background shader, doing a "for each of these regions, don't draw if we're behind one" feels like it'd be very expensive.  Also, I don't know how we'd handle that since the holes would project back onto the spherical background mesh, creating odd shapes that would have to be computed at some point and per-frame.

If we're targeting only content, I think there's a simpler (but still hacky) approach we haven't taken yet.  Based on where content is located, we can figure out which background triangles aren't visible, and skip drawing them.  This would be easier if the triangles behind content were at the end of the vector, and we were just choosing when to stop drawing.  This gets worse when considering fullscreen and content repositioning though, and it scares me because it adds quite a bit of complexity in exchange for only saving overdraw on part of one big quad.

I wonder if metrics could help us track the impact / potential gains of addressing this.