My dad always told me
"There's no replacement for displacement"
That certainly holds true in the world of projectiles-mass is for more desireable than excessive speed.
Now, there is a point where too much mass can become detrimental, but this can easily be calculated. find a good muzzle energy calculator- and plug in some figures. It will get you close.
Game can certainly react to/and sometimes successfully dodge projectiles, so set yourself up for the distances you generally hunt.
Naturally, you are gonna want more speed at longer distances, but I'm finding that 30 yds is a moderate to long distance with my shooting ability. So if my arrow is traveling a mere 150 fps- the arrow will get there in under a second.
Keep in mind that mass will also help to maintain your speed.
I am certainly no authority-but if you are looking to bump up speed, try to get it from the bow setup-maybe a string with less strands. If your arrows are tuned well, you could sacrifice fletch length, height, number-but I would not expect much from this-as it only reduces drag, not really weight.
Looks like you have plenty of energy to do the job though, and make sure the business end of that projectile is plenty sharp.
farmer