The weight of the quiver (and the arrows that you put in it) along with how and where it is attached, the weight of the bow, and how you grip the bow can all be factors.
At Eagle's Flight Archery we make the ultralight champion. Our 3 arrow quiver weighs 3.2 ounces, the 4 arrow standard size Cherokee, Maxi, and Navajos weigh about 5 ounces. We make the one for people who don't want to tune to the quiver, those who don't want to feel any extra baggage on their bow. We like to say, "travel light with eagle's fllight."