What does performance testing assess?

Performance testing primarily focuses on evaluating how a software application behaves under specific conditions, particularly when subjected to various levels of load. This includes measuring the system's speed, responsiveness, and stability as user demands increase. The objective is to ensure that the application can handle anticipated traffic and data processing without degradation in performance, which is critical for user satisfaction and operational efficiency.

Performance testing typically encompasses different scenarios, such as load testing, stress testing, and endurance testing, all aimed at identifying potential bottlenecks and ensuring that the system can maintain consistent performance levels. In contrast, the other answer choices pertain to different aspects of software testing; functionality pertains to operational correctness, security focuses on identifying weaknesses, and usability assesses the ease of use and overall user experience. Thus, focusing on speed, responsiveness, and stability accurately reflects the core intent of performance testing.