Actually yea, they are suppose to perform better at peak weight. When you let poundage off, your shortening your A2A length and increasing draw length. But, its nothing really serious to worry bout. Anywhere from half weight recomendation to full weight is where you should be. Plus, if your only goin to shoot 60 pounds on a 70 pound bow, why not just buy a 60 pound bow in the first place? Im sure people will argue with me on this, but this is just my knowledge on the subject.