Even an average selfbow is only slightly, if at all, slower than your average fiberglass laniated longbow these days. Unlike you, the companies don't spend a great deal of time trying to lighten the tips, achieve a perfect tiller, or design the bow to
your draw.
For example: my friend was shooting his Beart Montanna with me a few months ago. We were eaching shooting arrows that were 9 gpp, and my selfbow was noticeably faster. Later I put a FF Plus string on his bow and it picked up some speed, but not much more than my bow still. It wasn't until I
shot his bow that I realized it didn't shoot much better either (in terms of forgiveness or accuracy)! Sure suprised me