A lot has to do with the angle at which the string approaches the tips when at draw. The less the angle, the less stacking will occur. If you use a stringer for your bow you can recreate this effect. If you put your foot on the center of the string and pull you'll notice it's a lot smoother to pull than if you spread your feet out about two feet, at which point it's much harder to draw and brace the bow.
Generally, longer and/or recurved bows have less stack because the string angle will be less at full draw. Also, slightly stiffer tips (or even static tips) work to reduce stack because they work as efficient levers to bend the inner 2/3 of the limb, all the while reducing string angle. Of course, this all depends on your draw length, the bow's materials, etc.
Here's a picture of the smoothest-drawing bowing I own. It's a horse bow that I finished several months ago. Notice the string angle at full draw and the way that the siyahs work at stiff levers. VERY efficient, smooth, fast design.
Hope my $0.02 helps. Others will no doubt shed more light on the subject.