13% cpu usage at the lowest c-state is a also very different than 13% at an elevated c-states. I've recently spent a lot of time analyzing c-states/p-states and the power mgmt modes of the GPU. After learning more about the complexity behind the clocks, bus speeds, etc. underlying each state, whenever I hear someone quote a utilization number of a minor workload, I want to know at what power state.

Not to take away but the author's point, just an aside that utilization numbers can be a lot more complicated when there are dozens of energy states and the utilization might be utilization at a particular state rather than utilization at maximum power