UBBCode is disabled on new accounts, to discourage spam (no clickable links). It'll work now, though.
Running the game in Win 9x compatibility mode will restrict it to a single core. I don't know if that will help with the CPU usage when minimized.
One of the threads seem to hover around 7% or 8%. I think most of the time is used in a main thread.
I know the input is handled in the render loop - tried the game on my onboard while zip-tie'ing a new fan to my graphics card. It lagged so hard (~3 seconds/frame) I had to hold down clicks until the frame advanced just to have it register mouse up and down. X-)