Well, since speed will vary with draw length, brace height, arrow weight, how much junk is on the bow, how the strings are rigged - and pair that with the fact that most people have no idea what their draw length is (they confuse it with arrow length), have no idea how heavy their arrow is (can't weigh it on a bathroom scale), and probably have no idea what their speed is(they all think it's 300)- Kinetic Energy is Spanish to a layperson. We might as well be talking about the Tooth Fairyor Leprechauns.
Most people, however, are smart enough to know what their draw weight is. On average, a 55# bow will push out 55# of KE - ballpark. On average, a 40# bow will push 40# of KE. Since you guys know so much, I'm sure you figured that out by now.
If you're equally perceptive, you might have noticed that you don't see many deer checked in for the annual HNI buck contest that were killed with 40# pea shooters. Same reason you don't see so many deer shot with .22 Hornets or Slingshots.
I'd really like to see y'all put your money where your mouths are, and order a 40 pounder for this fall. Maybe you could do a little "Get in Shape Girl" warm-up, drive to your hunting spot in your Barbie Jeep, hop out with your 35# deer slayer, and go at it. I figure if you get one early, maybe in September - before it gets its winter coat or grows to full size, you might be able to shoot a fawn right off the tit, and the heavy winter furwon't cause your arrow to bounce off.