The whole "send surfaces only instead of whole chunks" bit now works properly, so I thought I'd show you guys a video.
(Omagosh I'm allowed to embed Youtube videos again? yay!)
It seems the screen recorder didn't only kill the frame rate as per usual, but also messed with the occlusion queries. So you'll see the occasional hole in the terrain. Let's see if I can figure out why this happens...
Edit: Fixed it by changing the occlusion system. We'll leave that for another blog post. In the meantime: