[alkonaut]

> So if you're in space, and you're flying nearby a big ship full of triangles, such as an imperial star destroyer, you run your framerate down to the ground if you render even only 5% of it, as it renders everything else as well.

There is limiting of overdraw (not rendering the same pixel multiple times) which is easy with Z-buffers. There is frustum culling (not rendering triangles that are outside your FoV or facing away from you) already of course.

The final type of culling is occlusion culling which is avoiding rendering that starship because it's on the other side of a planet from your viewpoint (for example). That's not a feature of 3.X but it's a feature of 4.0. The technical details are pretty interesting, it uses Intel Embree (the raytracing library) to do a low-res raytrace to find the occlusions.