Making a Fast Website - Scirra.com: "Jakob Nielsen is an authority on usability and has studied response times extensively. He notes that response times of:
Up to 100 milliseconds is perceived as instantaneous response
Up to 1 second will be noticed by the user but their thought flow will remain uninterrupted.
Over 10 seconds is also mentioned but this shouldn’t be applicable to normal websites which is the focus of this blog. If your site takes longer than 10 seconds to load something is probably critically wrong!"
'via Blog this'