Experimented with the demo of Circle today what no-so-fresh results.
Circle may be too much for Ableton to handle. Even on a completely empty set my 2.4 GHz Intel Core 2 with 2GB of RAM, several patches cause Ableton's (7.07) CPU meter to jump well above 80%. I can't imagine what would happen if I tried to use this Audio Unit on a larger session.
Any suggestions?