Sounds like two problems. One, you don't know what IBO speeds are based on. Two, unless you're shooting something like a broom handle with a 20 inch draw, your bow is pulling about 35 pounds.[8D]

My bow is rated at 314. I only have 28 inch draw. I added a loop, peep etc and then a 450 grain arrow. I'm all the way down to 258 fps.