A fastener tool that drives a fastener into a workpiece includes a housing, a nose assembly, a driver, a motor, a flywheel, one or more sensors, and a controller. The controller is configured to adjust a speed of the driver based on 1) a difference between a first angular velocity of the flywheel measured by the one or more sensors at or before the start of the drive commencement and a second angular velocity measured by one or more sensors after the start of the drive commencement; or 2) a time difference between a first time after the start of the drive commencement when the driver and the flywheel are in engagement with each other and when the driver and the flywheel are moving at the same speed and a second time when the characteristic of the motor meets a predetermined threshold.