UPDATED: Everything you wanted to know about web performance but were afraid to ask

As mentioned when I first posted this popular entry, my plan is to keep this one-stop shop for performance stats up-to-date as new data is released. Here’s a summary of what’s been added:

A user who has to endure an 8-second download delay spends only 1% of her total viewing time looking at the featured promotional space on a landing page. In contrast, a user who receives instantaneous page rendering spends 20% of viewing time within the promotional area. [Source: Jakob Nielsen]

Between 37 to 49% of users who experience performance issues when completing a transaction will either abandon the site or switch to a competitor. Of these, 77% will share their experiences with others. [Source: Sean Power, Metrics 101]

Users have faulty perceptions of time. For example, the average person will perceive the amount of time it takes a page to load as being about 15% slower than the actual load time. And later, in recalling their memory of how long it took for the page to load, they will remember it took about 35% longer than it actually did. [Source: Stoyan Stefanov, Psychology of Performance]

  • A site that loads in 3 seconds experiences 22% fewer page views and a 50% higher bounce rate than a site that loads in 1 second. Impact on conversions: -22%.
  • A site that loads in 5 seconds experiences 35% fewer page views and a 105% higher bounce rate. Impact on conversions: -38%.
  • A site that loads in 10 seconds experiences 46% fewer page views and a 135% higher bounce rate. Impact on conversions: -42%. [Source: Strangeloop]

You can read the post in its entirety here.

Related posts: