Performance Testing: Load, Stress, and Soak Testing
Performance testing validates that your system performs acceptably under expected and peak load conditions. It is a critical part of production readiness for systems with significant user traffic — particularly before major launches or traffic events.
Types of Performance Tests
- Load testing: Simulates expected normal traffic levels and validates that response times and error rates meet requirements under normal conditions
- Stress testing: Increases load beyond normal levels to find the breaking point — at what load does the system fail? How does it fail (gracefully or catastrophically)?
- Soak testing (endurance testing): Runs sustained load for an extended period (hours or days) to detect memory leaks, connection pool exhaustion, and gradual performance degradation
- Spike testing: Sudden, sharp increases in load — simulating traffic spikes from viral content, marketing campaigns, or sale events
- Scalability testing: Tests whether the system scales as expected — does adding more instances linearly increase capacity?
Performance Testing Tools
- k6: Modern developer-friendly load testing tool with JavaScript scripting
- Gatling: High-performance load testing with Scala/Kotlin scripting and good reporting
- JMeter: Established tool with a large ecosystem, Java-based
- Locust: Python-based load testing — easy to write complex user behaviour scenarios
When We Perform Performance Tests
We include performance testing as part of launch readiness for applications expecting significant traffic. We also recommend load testing before major promotional events, infrastructure changes, and significant new feature deployments.