I guess I am a little lost by your question. Are you asking how efficient the bow can transfer energy from the bow to the arrow? If so, a lot would depend on the weight of the arrow. A bow would be less efficient on a very light arrow (say 5 grains per pound) as compared to a heavier arrow (say 9 grains per pound). On the lighter arrow, the energy not used still has to be expended through different medians such as shock, noise, vibration, etc.