Keep in mind that the percentage in Activity Monitor is 100 % per core, so a 10 core CPU can go up to 1000 % usage. So 60 % means 60 % of a single core not of the whole CPU.
I fell for that shallow analysis myself once when I noticed just how apparently bad the gpu usage was for a big of animation in a web page, until I noticed my 30% load gpu still drew as much wattage as it did on idle.