#but it has to suspend jobs in order to react to UI commands

[tap-tap-tap-im-in]

And for further clarity. By saturated I just mean the CPU was consistently not processing tasks quickly enough. It was sitting around 150% utilization or about 6.00 on uptime or top for a 4 core processor.

Well within reasonable utilization for spike loads, but not something I would want to sustain for over the course of a full movie. That's where the CPU would start to use the boost clock speeds, increase power draw, and be potentially unresponsive if another intensive load needed to start.