WOW there is no deadset answer for that question. There are so many different styles of longbows and every design varies on its efficiency. Most longbows have a much smaller riser and are not center shot so you need a lighter spine to bend around the riser upon release. But there are always exceptions and some of the newer designed longbows are real screamers and are as efficient as most recurves. Personally when I think of the classic D shaped longbow my mind says lots of handshock not impressivley fast and quiet. When you go to the R/D longbows I think faster way less handshock and still quiet. Recurves have more mass weight in the riser which lends itself to a steadier bow arm and are normally centershot so they can shoot a broader range of spines with good results. Well I guess thats my .02 and I am FAR from an expert on anything so hopfully more folks chime in.