Now think about twirling a rod about its center as opposed to swinging it about by one end. This is why the moment of inertia is so much greater for the axis through the end. Again this is because of the distance of the mass from the axis. So objects with mass concentrated near the axis of rotation will have smaller moments of inertia and thus will be able to spin faster. Rotational dynamics very similar to linear dynamics with change of variables.
Moment of inertia depends on mass distribution, shape, and choice of axis.
The physics of karate.