The biggest factor in cat speed is:

A) light weight - we have wide beams used as leverage so we don't have to carry lead to counteract the power of the sails. We can accelerate much more quickly to puffs AND we don't have to displace an inordinate amount of water to overcome the lead in a keel.

B) the hull length to width ratio of our cats is greater than 11 (i.e. 1 foot wide and more than 11 feet long). All hull shapes push a wave of water in front of them while they are in displacement mode. Generally sailboats don't have the power to climb up on top of this wave and therefore cannot ever move faster than the wave. Planning mono's can get up on top of the water reducing their drag enough to climb their bow wave. Cat's, or any other hull shape with the length to width ratio greater than 11/1 do not have to contend with the bow wave and are not limited by the speed of it.