Usability relies on good performance. No user wants to wait more than a few seconds for data. Anaplan defines usability as both response time of the Anaplan platform and the visual appeal of the model.
You may experience poor model performance long before actual testing begins. Work to resolve performance issues sooner rather than later. The Rapid Forensic Analysis Job Aid provides various model attributes, the analysis tools used to determine that there is a performance issue, questions to ask and remedies to try.