Performance quality is the ability of customers and end users to complete tasks in reasonable time and with reasonable responsiveness. For some software, value comes from users being able to complete tasks quick enough; too slow and it may become useless for its purpose or leave waiting users annoyed. However it’s also possible for software to respond too fast not giving users a chance to react (Nielsen, 1993).

Performance quality is prioritised by stakeholders when timing is critical to delivering customer or end-user value



Key supporting metrics may include:

  • Wait time between user interactions (input and expected output) in completion of a task



Opening a document on the computer could take 10 seconds, while annoying, may not be a serious problem to a user making performance quality low priority. However timing is important to real-time computer games or stock trading software where even a delay of half-a-second could mean serious loss or harm to a user. Performance bugs occur when users feel their productivity is being hindered and they’re having to wait for the software to “catch up”. A performance “showstopper” occurs when a user is kept waiting too long and abandons a function in completion of a task or the software itself “times out” and never completes.

Threats to performance value may include:

  • Long or unnecessary loading times
  • Unnecessary or poorly designed loading screens giving the illusion of poor performance
  • Delays between user input action and expected output response
  • Screen elements or messages disappearing off-screen before a user has chance to read or react
  • Bottlenecks in the system
  • Inefficient, unoptimised code
  • Insufficient system resources or missing cache

Some famous examples include:




Heuristics to test for performance quality may include:

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  • Nielsen, J., 1993. Usability Engineering. 1st ed. San Diego, CA: Morgan Kaufmann, Ch. 5. Available at: Link

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