Remove unused influences from a smooth skinned
surface
To enhance Maya processing speed and make the Paint Skin Weights Tool easier to use, you can disconnect joints and influence objects from a smooth skin that has all of its skin weights at 0. The Paint Skin Weights Tool becomes easier to use because the unused influences do not appear in the Influence list for the skin.
For example, suppose you smooth skin a left foot stocking to a human skeleton with the default options. All joints in skeleton will be connected to the stocking as potential influences, but only the joints closest to the left foot stocking will have nonzero weights.
If you select the elbow and rotate it, Maya computes the skin on the stocking to see if there are any nonzero weights. If you select the stocking and remove the unused influences, the elbow and the other zero-weighted joints will be disconnected from the stocking and performance will improve.