Performance management starts at the very beginning of the hiring process when a job is defined. From there, it involves continuous evaluation of the employees' work to ensure it meets or exceeds the employers' expectations.
One cannot just hire employees and leave them to do their best. Managers need to monitor the performance of each individual after setting SMART (Specific, Measurable, Attainable, Relevant, and Time-based) goals and defining their role in the company.