A surgical stapling instrument comprising a housing, an end effector, and a firing system is disclosed. The end effector comprises a first jaw, a second jaw, and a replaceable staple cartridge. The first jaw is rotatable relative to the second jaw. The firing system comprises a firing actuator, a firing member movable from an unfired position toward a fired position during a firing stroke, and an electric motor operable by the firing actuator to advance the firing member through the firing stroke and retract the firing member back into the unfired position during a retraction stroke. The firing actuator is operable to slow the retraction stroke.