And apps don't eat cycles to check if the
computer is idle, they GET cycles when it is. (Unix-based system have this
neat thing called "nice-levels" and any "expert" should know what that
means).
There are some shareware and terminal commands which show the processes running and how much CPU they are taking. I was shocked to find 40 things running at one time - all kinds of hidden processes. And I was also shocked to find out the Photoshop was taking a huge hit on my CPU even when totally idle.
I worked on a song last week - it had about 8 audio tracks, maybe 8 virtual instruments and some plugs. And yet I was getting audio overload messages in Logic. So I feel I need all the power and stability I can get.