I just want the speed to help with deer jumping the arrow.
You can forget that. There isn't a bow or crossbow made today that can fling an arrow fast enough to negate a deers reaction time.
increasing the weight of my arrows will do all that?
Absolutely! You would be surprised how quiet a bow will get when you shoot a 500+ grain arrow. In fact if you want to beat a deers reaction time this is the only way to do it. The quieter the bow the less the deer will react to the shot.
A bow becomes more efficient with heavier arrows. The heavier the arrow is the more energy that the bow is able to transfer to that arrow which results in greater penetration. Another benefit to heavier arrows is less wear and tear on the bow. Since the bow transfers more of its stored energy to a heavier arrow there is less "left over" energy that the bow must dissipate through vibration and noise. The less the bow is vibrating the less wear and tear.