My iPhone is behaving slowly, so I am trying to watch CPU usage in Instruments.app on a Mac to see if any particular process is to blame. But the CPU activity in the "Activity Monitor" instrument doesn't make sense to me. Right now it's showing a steady CPU Total Load ranging between 30% to 40%. But in the list of processes below, they add up to less than 1% in the %CPU column. So what is actually being measured at 30% and is there a better way I should be diagnosing this?