It seems like a lot of people are more focused on speed then the kinetic energy of the arrow. The denser arrows shoot at a slower speed but are going to give you better penetration (assuming you are still getting reasonable fps). I know some guys that are so hyped up on speed they neglect that their arrrows are porpoising because it is shooting TOO fast. Although I don't think there is anything wrong with trying to make a bow as fast as possible, I think it has become a little overrated.