I take my first enema of a series slowly. After the "road is cleared" a bit I raise the bag to take them faster. Overall, I like taking a fast enema. I haven't noticed any significant increase in cramping taking them fast. The fastest I have taken one is hanging the bag from the shower rod and kneeling bent over the tub. I have to be pretty well cleaned out to do that, but it does a good job finishing off a good clean out...at least for me.