On my late 2013 13 inch retina Macbook Pro its the same. Constant CPU load of 60-70% on one core and worst of all the fans spin up badly and the load sucks the battery dry in no time.
Now i understand this is a high end gaming engine we talk about here, but Unity4 for example idles at around 5-15% and only taxes the GPU when i actually do something in the scene view, otherwise it seems to not tax the GPU at all.
This results in normal temperatures and also much better battery life. Currently thats the main factor holding me back from switching to UE4, would be so cool if you could fix that somehow!