that X causes a high load on moving windows is 'normal' and nothing to worry about. I have a dual core and a 6600.. and moving a window around fast can give up to 70% load in htop.
Your video load is strange.
Do you have a high load, if you only use one screen?
Can you make sure, that you are using xv?
Oh, and you could try turning on backingstore.
(and please, don't replace the logs. give every single on a unique 'name'.. not really important, but it prevents confusion