A method and apparatus is disclosed for determining an objective measure of performance of an extended finite state machine. Many modern complex systems, for example, computer communications protocols and computer or machine user interfaces, can be represented as extended finite state machines. A formal description of the extended finite state machine is employed to obtain a canonical form description. The canomical form description, combined with a service description, is used to generate a list of canocial state transitions transited by the extended finite state machine to perform the service. From this list, an objective measurement of performance, e.g., the time required to perform a particular service, is obtained. This objective measurement may then be used as desired, for example, to select an optimum extended finite state machine from a plurality of extended finite state machines.