I find what eats most of my CPU is the MCGlidHost.exe which is the background EPG scan, I believe it becomes active when a tuner is not in use and because I have 5 tuners (2x DVB-T, 2x DVB-S and one DVB-C) it can be quite annoying but i just reduce the priority of the service. one instance of DVBLink and TVSource use between 5% and 10% when viewing SD but around 30% on HD on an Athlon 7750 @ 3Ghz