As the bow is shot, the string on a conventional compound bow pushes the arrow more than twice the distance as when a crossbow is shot. Therefore, to produce the same arrow speeds, a crossbow must have more than twice the draw weight of a compound bow.
Because of this much shorter “power stroke” (draw) on the crossbow, it must have much heavier limbs. The powerful limbs move a short distance and stop quickly when an arrow is shot. Therefore, the crossbow must have more physical mass than a compound bow to absorb the shock. This short, heavy power stroke means the crossbow will create more noise when discharged than the conventional compound bow.