No culling of a block that shows up absolutely everywhere.

What it should look like (and does w/ connected grass disabled):

What it actually looks like:

This makes the typical world's surface about 5 times more expensive to render than it ought to be.

Well, this is embarrassing. And this has been going on ever since 2.0. Thanks for noticing. I never knew that spectator mode has noclip, but I'll use it from now on.

Fixed in 2.1.4