In archery, arrow speed is a big deal. Faster arrows have flatter trajectories. This means that small errors in range estimation are less of an issue. And, all other things being equal, if two arrows of the same weight are shot from two different bows, the one with the faster arrow speed will penetrate more. Obviously, it will get there slightly sooner too, which means the animal has less chance to dodge the arrow.
That's the up side of speed.
On a traditional bow, increased speed can be achieved in a number of ways. Pulling a heavier poundage (whether by getting a heavier bow or increasing your draw length on your existing set up), setting your brace height lower, finding a slicker release or using a lighter string or lighter arrow can all add a few feet per second to the arrow's speed.
But there is a down side to all this too.
First off, most people shoot bows better with bows of lighter draw weights. That's because they have more control over the draw and sight picture when muscles aren't at the straining point.
Then there is the fact that the lower the brace height, the fussier a bow is to shoot. Too low and arrow feathers hit the shelf on launch. Or wrist slap occurs. Moreover, when an arrow leaves the bow closer to the handle, as it does with low brace heights, it has to go around the handle a little more dramatically. I liken it to the difference between driving a car and swerving around a lamp post. Obviously, if you start the evasive maneuver further out it is going to be smoother and easier to control.
All this is to say lower brace heights exaggerate the effect of archer's paradox, which is the technical name for an arrow's path around the handle.
There's never harm in finding a slicker release if you can shoot it well, unless that release isn't going to stand up to the rigors of the hunt.
There are, however, down sides to shooting lighter arrows and strings. Both are noisier, for one.
In simplest terms, a heavier arrow absorbs more energy and slows the bow string down more. All other things being equal, a heavier arrow penetrates better, too. This time let's think of catching a ball. What are you going to feel more, a baseball thrown at 60 mph or a lead ball of equal size thrown at the same speed? The latter would likely kill you, right? Heavier arrows also carry much more momentum. Imagine two wagons rolling down a hill. One is empty, the other has rocks in it. Which one is going to be easier to stop?
Lighter bow strings move faster, vibrate more and transfer more energy to the bow limbs. A bow string with silencers on it is heavier but obviously quieter.
These are the down sides of setting your bow up strictly to maximize arrow speed.
I'm not saying you shouldn't strive for faster arrow flight. But you should understand the price of it and find a proper balance between speed, noise, penetration and accuracy. This, after all, is the hallmark of a well-tuned hunting bow.
Accuracy should always be the major consideration, of course, but after that, you need to keep the game and way you hunt in mind. If you never shoot game at more than 20 yards, for instance, what is the optimal balance of noise level, penetration and speed required?
Think about that. Then, experiment until you achieve just the right balance.