The drop was to be expected. The effect eats fillrate for breakfast. The higher the values, the more. Usually, the values stand for the number of iterations that are applied in each stage. You *may* apply 2000 blur steps if you like, but...well...it will be sloooowwww. It's similar to the Water-effect: Play around with the values to find a good compromise between performance and quality. There's no exact rule to follow when choosing the values, which may be why the description is vague.