SAP Loadrunner from HP is an application that enables organizations to test the performance, stress/ volume of the SAP system to be deployed. If these tests were to be performed manually, it would require a large number of users generating data simultaneously. Loadrunner creates virtual users to simulate real users; and tests the system. As a test tool, it is integrated with HP Quality Center.
Read about it at http://veritysolutions.com.au/2010/12/12/sap-loadrunner-vugen-from-hp-a-primer/