How do different types of system performance testing differ?

System performance testing includes several main types, each checking different aspects of the application's operation under load:

• Load Testing — checks how the system operates under expected normal load. The goal is to ensure that the application is stable and responds quickly with a typical number of users or requests.

• Stress Testing — examines the system's behavior under extremely high load, exceeding normal levels. The aim is to determine the limits of stability and to see how the system behaves under overload (e.g., whether it crashes or recovers correctly).

• Stability Testing (or Soak Testing) — tests the system under constant load over a long period to identify memory leaks, performance degradation, and other issues that manifest over time.

• Capacity Testing — determines the maximum load the system can handle without degradation of quality.

• Performance Testing — a more general term that includes all of the above, aimed at measuring response time, processing speed, and other metrics.

Each type of testing helps identify different problems and optimize the system for real-world operating conditions.