When it comes to longbow design and speed, the key is the amount of mass in the working limb. If you ever notice the short longbows also have shorter risers, and the longer ones have longer risers. It's important to keep a ratio of riser length:working limb at the optimum (I know what it is too, +/- a bit, of course) But if you go too long with the limbs, putting the tips past that ratio, you'll have negative returns and it'll slow things down, all the while feeling very smooth while drawing, and that's totally fine if that's what you like but that can also add some hand shock. This applies to any longbow design D/R, Hill styled, etc.