I hacked another fix into CruiseControl.Net today and we now almost have an acceptable level of performance in my particular (some may say warped) circumstances. The trick was to hack the project trigger to be a "local project" trigger. By default the project trigger uses .Net remoting to talk to the CruiseControl.Net server where the project is hosted. In my case this meant that all of my project triggers (and there are lots!) were using remoting to talk to the server that they were running in; this looked like it could be a triffle inefficient so I hacked in a way for them to check the local server's projects directly. I'm now down to CC.Net taking between 0 and 4% of my CPU rather than 65-90%...