There is a simple experiment that anyone can do at home and will show the penetration difference derived from mass over speed. All you will need is a wrist rocket slingshot, a chronograph, a ping pong ball, a golf ball and a dozen roses.
Set up the chronograph in your living room with a blank sheetrock wall as the backstop. Take the ping pong ball and shoot it over the chronograph into the sheetrock wall as fast as you can and write down the speed. Next, take the golf ball and shoot it over the chronograph into the sheetrock wall as fast as you can and write down the speed. Note the difference in penetration on the sheet rock wall, lol. Give the dozen roses to your wife when she gets home so she doesn't divorce you over the hole in the living room wall.
PS don't really try this at home.
If we're strictly talking momentum, it is a simple function of mass x velocity (everything else equal).
Many shooters are over 400g without adding heavy inserts or broadheads over 100g.
Lets see some some calculations using the same bow. IBO = 315, 29.5" draw length, 66lbs draw weight, 15g on string.
M in lb-s, KE in ft-lbs:
400g taw, 281.6fps = .4997lb-s, 70.362ft-lbs
500g taw, 248.3fps = .5507lb-s, 68.381ft-lbs
600g taw, 215fps = .5723lb-s, 61.523ft-lbs
650g taw, 198.3 = .5718lb-s, 56.698ft-lbs
So, at the "bone breaking threshold of 650g, this bow actually produces less momentum and kinetic energy than at 600g.
Now this isn't real world, I'm just using calculators.
But I think it's demonstrative to the relationship between mass and velocity, much more than ping pong balls and golf balls and long range precision shooting.
In this case, the most significant gain in momentum happens at 500g and costs less than 40fps. Going to the bone breaking threshold of 650 costs over 40fps more than that at approximately .02lb-s increase in momentum.
Is .02lb-s worth more than 40fps?