This document discusses software regression testing and performance testing. It defines regression testing as retesting software after changes to check for defects in modified areas and unaffected areas. Regression testing happens at the unit, integration, and system levels and requires analyzing software changes and impacts. Performance testing evaluates a system's compliance with performance requirements by testing response times under various loads. It helps ensure applications meet customers' expectations as defined in SLAs. The document discusses performance testing tools and benefits of the approach while cautioning that performance testing is as much an art as a science due to the many variables involved.