I really should learn to be more patient and read the docs. Today I stumbled across Gentoo compiler caching. From the About ccache section:

ccache is a fast compiler cache. When you compile a program, it will cache intermediate results so that, whenever you recompile the same program, the compilation time is greatly reduced. In common compilations this can result in 5 to 10 times faster compilation times.

Sheesh. How much time have I wasted sitting around drooling on myself waiting for portage to build package XYZ?

In addition to learning to read the docs I should also probably learn to stop drooling on myself.