Website Response Times An Article by Jakob Nielsen www.nngroup.com Users really care about speed in interaction design...A snappy user experience beats a glamorous one, for the simple reason that people engage more with a site when they can move freely and focus on the content instead of on their endless wait. 0.1 seconds gives the feeling of instantaneous response. This level of responsiveness is essential to support the feeling of direct manipulation. 1 second keeps the user's flow of thought seamless. 10 seconds keeps the user's attention. A 10-second delay will often make users leave a site immediately. uxperformanceinteraction
Head and hand The blueprint signaled a decisive disconnection between head and hand in design: the idea of a thing made complete in conception before it is constructed. Richard Sennett, The Craftsman The preliminary sketch design