Slice it and clean it up?!
Thanks for the response:
I'm not sure that I can to be quite honest-been working on it for months. Does AE typically not respond well to bringing in lots of media?
Don't try and do a whole movie in AE. After Effects is for making shots or short sequences. Break up the projects. Organize. 3TB of source materials into AE's Project folder means linking, analyzing, interpreting, and generating previews for enough material to shoot a feature film. Bring in the shots you're working on, not the entire movie. If you need to do an entire movie, break that up to Scenes and make each scene a separate project.
Terabytes of data would also choke Final Cut Pro, Premiere Pro, Avid, or any other NLE if it was dumped in all at once. The only reason that a NLE can handle that much data is that there were some caches created when the footage was imported.