Summary: Overly fast interfaces are error prone and encourage users to rush through websites and other systems. Design to reduce interaction speed and increase users’ understanding and task success.
There is no doubt that the traditional emphasis on speed in user-interface design has gone overboard. Yes, there’s something to be said for fast response times and web pages that download immediately. And for decades, one of the 5 measurable quality attributes of usability has been efficiency: Once users have learned the design, how quickly can they perform tasks?