Try TuneUp utilities for cleaning and defragmenting Registry , cleaning up disk space ,optimization ,System protection , removing broken shorcuts , disk defrag and much more.
After you do all tahat stuff your PC will start and Run much better.
But it costs so you willl have to buy or download the trial
Or you can go to "you know where" not that i reccomend doing that if you know what i mean!
And for CPU usage i dont think it should be high if you dont do anything on your PC.
Try using the program above to shut off some programs that you dont need.