What does performance testing primarily evaluate?

Performance testing primarily evaluates the speed, scalability, and stability of a system. This type of testing is focused on determining how well an application performs under certain conditions, particularly under load or stress. It assesses factors such as response times, throughput, and resource utilization, which are crucial for ensuring that the application can handle expected user traffic and perform efficiently.

By examining scalability, performance testing helps to understand how the system behaves as the load increases. This involves analyzing whether the system can maintain performance levels when the number of concurrent users rises or when the volume of transactions grows. Stability, another key evaluation aspect, ensures that the application can operate continuously without degradation or failure.

In contrast, other options do not align with the primary objectives of performance testing. Usability relates to how user-friendly and intuitive the application is, which is more about user experience than performance metrics. Security focuses on the protection against unauthorized access and vulnerabilities, and completeness of test coverage deals with how thoroughly the system has been tested in terms of functionality rather than its performance characteristics.