I can't explain the speed thing but I got it. It's the techie part of archery/bowhunting. I have two set-ups. One for hunting and one for target and 3-d. My hunting rig is set-up with 4" feathers and 7-8 gr. per inch arrow. With that set-up I get more energy plus I'm not worried about shooting over 25-30 yds. My 3-d set-up is 5 gr.per inch and I'm more concerned with FOC cause I'm shooting much longer distances. Both set-ups are with carbon arrows. I found carbons are less critical to spine and more durable. My accuracy seems to stay the same regardless of my set-up or speed. That's the nice thing about this sport. You can go in what ever direction you choose or enjoy it all for different situations. I even shoot a little trad for fun but I'm always thinking compound and speed. JERRY