If you have that many users, I don't know if Python really is suited well for such a large scale application. Perhaps it'd be better suited to do CPU intensive tasks it in a compiled language so you can max out proformance and then possibly use a UNIX-style socket to send/execute instructions to the Python interface, if necessary.
Sorry I really couldn't be of much help -Wes -- http://mail.python.org/mailman/listinfo/python-list