Wedge: As far as I understand it, skeletal animation is more CPU-intensive because it must compute the vertex displacements from the computed bone position, (including weighting and blending) instead of just reading off a list of coordinates from a frame of vertex-based animation.
This does reduce the RAM requirements though, which might help speed up RAM-limited systems. It also allows more flexible characters, which is a Good Thing.
I think it would be theoretically possible to temporarily cache the results of the vertex calculations so as to make the trade-off back to low-CPU, high-RAM usage, but it would be difficult to get right and probably wouldn\'t provide much of a performance boost.
