In my opinion, the nature wood fibers especial yew have the least energy loss or heat loss. that's because the natural selection. the more lams, the more glue is included in the bow, which as a buffer raises the heat loss. some body may argues that why most tri or quad lams bow has the higher speed than self bow. 1.Not each wood fibers could be excellent as yew. 2.using denser belly wood and powerer backed lam such as bamboo can reduce mass. 3.more important point is that the lams give the reflex, which stores much more energy than a straight self bow. that's why in a warbow flight competition the straight lams bows didn't show too much advantage than self bows and why a recurve horn bow has higher speed than a self yew bow, but supposing the poundage is up to 150 or more, the higher heat loss would be a significant negative factor.
