Electrical surgical instrument with differential rate of closing motion speed

A surgical instrument comprised of an end effector having two opposing tissue-compression surfaces, wherein at least one of the tissue-compressing surfaces is movable with respect to the other of the tissue-compressing surfaces, and a handle connected to the end effector. The handle comprises a power source, an electric motor supplied with power from the power source, and a closure assembly comprising a drive part that is selectively moved by the motor along a drive-part axis and is operatively connected to the end effector such that, when the motor is supplied with power, the drive part advances the movable tissue-compressing surface towards the opposing tissue-compressing surface at a differential rate of speed dependent upon a position of the drive part along the drive-part axis.