We run our own home grown data collection program using the MI.  We collect
"heaps" of statistics and the job only uses about 1,000 CPU seconds each 24
hours.
 
It seems fairly efficient for the amount of work it does.
 
I am a little unsure if it is the MI job which is supposed to put a load on
the system or if it stresses the other processes.
 
Regards
 
Bryan O'Halloran