Not sure why a CB would be considered inefficient but my horton supermax has good stats. They are; draw weight-175, power stroke is 14", arrow length is 20", arrow speed is 320 fps and KE is 95. Horton Has six CB's thathave KE above70 and the slowest one being 270 fps. I think the only one that is slower is their steel force modle and its just a entry level CB. I took mine to the local bow shop and with carbon arrows it shoots at 327 fps. I just went to mathews web site and it looked like they average around 230 fps to 320 fps and thats AMO to IBO. Not sure but I think IBO is like the perfect world conditions for that speed, not sure but could be wrong.Also they did not list KE, not sure why but maybe as Arthur said its directly related to draw weight. Thats why I like my horton, Take it out of the box and it shots what it said it does with out alot of money in extras.