Definition: Performance regression testing checks that newly developed or integrated features have not made the overall system slower or less stable. It re-runs performance tests against the integrated system after changes, usually using a maintained set of performance scripts known as a regression pack.
So what? A feature can perform well on its own but still slow down the wider system once integrated. Performance regression testing catches these bottlenecks, along with configuration, hardware sizing and infrastructure issues.
Examples: Re-running a suite of end-to-end performance scripts each sprint after new features are merged. Scheduling performance regression runs overnight or at weekends when time or test environments are tight.
