[Milhouse]

The only obvious difference between your threads and my threads is you have "4*[{CECAdapter}]" threads - I've disabled CEC in XBMC as my monitor has no CEC support.

What happens if you turn off/disable CEC - any change?

Edit: I've enabled the CEC adapter on my Pi and after restarting XBMC I also have the "4*[{CECAdapter}]" threads but after a few minutes load is hovering around 20% so that's not likely to be the reason unless libcec is going bananas on your system for some reason.