If a page takes too long to load, after how long – generally – will a user give up and re-load or go elsewhere? What studies have been done that measured page load time and user satisfaction or abandonment?
Jakob Nielsen has an excellent article, Website Response Times (June 21, 2010) in which he explains why website response times still matter.
0.1 seconds gives the feeling of instantaneous response — that is, the outcome feels like it was caused by the user, not the computer. This level of responsiveness is essential to support the feeling of direct manipulation (direct manipulation is one of the key GUI techniques to increase user engagement and control — for more about it, see our Principles of Interface Design seminar).
1 second keeps the user's flow of thought seamless. Users can sense a delay, and thus know the computer is generating the outcome, but they still feel in control of the overall experience and that they're moving freely rather than waiting on the computer. This degree of responsiveness is needed for good navigation.
10 seconds keeps the user's attention. From 1–10 seconds, users definitely feel at the mercy of the computer and wish it was faster, but they can handle it. After 10 seconds, they start thinking about other things, making it harder to get their brains back on track once the computer finally does respond.
He cites his Response Times: The 3 Important Limits as coming from accepted research as old as 40 years.
Short answer: roughly 3 seconds for more than half of users.
In Web Performance Today's Cheat Sheet: Everything you wanted to know about web performance but were afraid to ask, the first point addressed is the effect of page-loads.
In 2006, the average online shopper expected a web page to load in 4 seconds. Today, that same shopper expects your page to load in 2 seconds or less. [Source: Forrester Consulting]
Users who experience a 2-second site slowdown make almost 2% fewer queries, click 3.75% less often, and report being significantly less satisfied with their overall experience. [Source: Microsoft and Google]
- 57% of online consumers will abandon a site after waiting 3 seconds for a page to load.
- 9 out of 10 people will not return to a site after a disappointing experience.
- Of these, 3 will go on to tell others about their experience. [Source: PhoCusWright]
Other information in the article (all cited as in the quote) includes the effect of millisecond improvements in page-load times on page-view times, the effect of page-load times on time spent viewing advertisements, and the various effects of page-load times on revenue for e-commerce sites.