To optimize an automatically optimized machining time for machining a workpiece in a machine tool, an original parts program is loaded into a machine tool controller. The machining of the workpiece using the original parts program is simulated, where a motion path generated by the original parts program in the machine tool is determined. The motion path is classified into at least one area of potential optimization in which there is no workpiece contact. The at least one area of potential optimization is assigned a tolerance space. An optimized motion path is determined within the tolerance space. The machining of the workpiece using the modified parts program is simulated. The optimized motion path is displayed and marked. Once a user has approved the modification in the parts program, machining of the workpiece takes place using the modified parts program.