Calculating Lean Process Capability. In a typical manufacturing environment, processes are considered Lean when the efficiency of the process is 25 percent or more. Total time includes the setup, changeover, maintenance and scheduled downtime. In a transactional environment, most of these measures have no counterpart. The equation is therefore modified to: A transactional process is considered Lean when the execution time is less than one third of the delay time, or about 25 percent of the cycle time.