I'm with MilDot... Even if you drop 100 gns in arrow weight and strip down the string accessories, I doubt you could see much more than an extra 20 fps, and you'll have to use a chronograph to see the difference. It's just not enough to really change your trajectory or sight settings. And you'll be giving up some penetration potential to do it.

If you want significantly faster arrows, you'll need more draw weight or a bow that'll give you more speed. If you decide to cut the arrow weight for what little extra speed it'll give you, you'd need to increase the draw weight a bit anyway, just to keep the same penetration capability.