Which aspect does heuristic evaluation primarily focus on?

Heuristic evaluation primarily focuses on user interface compliance because it involves a systematic examination of the user interface against established usability principles, also known as heuristics. During an evaluation, usability experts review the interface to identify usability problems and assess how well the design promotes a positive user experience. This method emphasizes the importance of intuitive design, navigation, and overall interaction quality, which directly contribute to user satisfaction and efficiency while interacting with the software.

In this context, emphasizing user interface compliance allows evaluators to pinpoint areas that may lead to confusion or inefficiency for users, helping to inform design decisions that enhance usability. Other aspects related to system performance, such as system load capacity, user input data management, or database interactions, are not the primary focus of heuristic evaluation, as they pertain more to functional and technical performance rather than usability and user interface effectiveness.