Yes, I work for Larian (forum moderator, etc). I wasn't hired until after the game was in development (start of 2012), and am not in Belgium, so I have limited knowledge of things going on behind the scenes that I am not directly involved in.
I assume there are some general CPU optimizations yet to be done. With a Core i5 3570K (16GB RAM, ATI HD7870) my CPU usage is similar to what you reported above (running around at the start of a new game, I get 60-80%, 10-20%, 10-15% and 30-40% for each core, with a total about 30-35%), but I don't have any performance problems (minor stuttering if I try to play on high at 2560x1600).
