One method of speeding up a game engine is to use a BSP-Tree (Binary-Space Partitioning Tree) to subdivide and sort your game's world geometry.

This is done by dividing up, sorting, and storing polys in a BSP Tree in a such as way as to denote their relationship to one another (i.e. being in front of or in back of another poly). Once the BSP tree is compiled or built, the engine can quickly decide whether or not it should render certain polys based on the view’s current location within the world.

Here's the [FAQ.]

[GameInstitute.com] Has an interesting more info and a course on BSP. Prolly not worth $125 though.

Oh, one thing I was going to mention that since our game will likely be in space, this algorithm isn't that necessary for us. In space, the objects are sparsely populated, so I don't think cutting down on the polygon count will be that important. Still, it was an interesting read.