Loren Kandel shares a workflow tip that he uses for After Effects where he runs more than one instance of Ae so that he can render on one, and keep working on the other.
Certainly there are other ways to go about this, such as using the Ae BG render script, or even using Adobe Media Encoder for rendering. This is just something that Joren like to use as he works. With a bit of hackery, you can get your computer to run multiple instances of an application. Here, Joren shows you how to do this with After Effects.