Disk activity -> CPU waiting i.s.o. idle?

Hello all, When I create a lot of disk activity (copying files for example), my CPU appears to be spending a lot of time 'waiting' i.s.o. being 'idle'. I'm using software RAID-0 configurations for my disks (for the moment). Is it normal that it spends this much time waiting? Is this a result of my use of software RAID? Would it be different with hardware RAID? Regards, Pieter