The difference between a well-tuned query and a poor one is enormous, both in the elapsed time and the CPU usage. It is common to find Improvements of a hundredfold.
Too true. I've just tuned a stored procedure to reduce CPU usage by over 30 times, reads by over 10,000 times and duration by over 100 times. (I didn't write the original sp I hasten to add!).
Lempster