You have a slight misconception here. There is not a bow made that doesn't shoot an arrow that does not arc. The laws of physics are what they are and nothing can change them. An arrow is dropping from the time it leaves the bow till it hits something to stop it.

Yes, adding speed will diminish the drop to some extent, but not as much as you'd think. I've done my own shooting tests years ago to prove it to myself. I had a bow shooting 290 fps and sighted in at 35 yards. I bumped up the draw weight and shot the same arrow at 304 fps. Shooting the same 35 yards the difference in point of impact was just about 1 1/2" higher. Not enough to make much difference at any wild game animal or 3D target, and the toll on my shoulders told me it wasn't worth it either.

Also, I've tested several bows shooting a measely 264 fps that when sighted in for 25 yards placed an arrow into an area the size of a deer's vitals anywhere out to about 32 yards without holding high or low. Roughly 4" low at 32 yards. In practical terms I figured 30 yards to be acceptable at 3" low. So if I wanted to extend that to 35 yards I'd just sight the bow in at about 28 yards and have to hold about 3" low for short distances of 15 to 20 yards.

There are a lot of ways to bump up the speed. Cleaning any junk off the bowstring can help as can shooting a lighter arrow. If you're hunting mostly deer then arrow weight should not be an issue shooting at 70#. IMO jumping up to 80# is not the best solution.