I seem to recall the whole thing was muted in favour of the bounced output, but maybe not.
I just replayed the demo and was quite impressed by the even distribution of load over my 8 virtual cores (all tracks active). All 8 varied between exactly 20 and 30%. I also noticed that while virtual core 1 in the performance graph in Sonar shows a bit higher than the others (which are almost exactly equal) in the Windows task manager all 8 are essentially equal.