Akamai consulted those who shop regularly online to find out what they like and dislike about e-tailing sites. About half of mature net-shoppers - who have been buying online for more than two years or who spend more than $1,500 (£788) a year online - ranked page-loading time as a priority.

It found that one-third of those questioned abandon sites that take time to load, are hard to navigate or take too long to handle the checkout process.

The four-second threshold is half the time previous research, conducted during the early days of the web-shopping boom, suggested that shoppers would wait for a site to finish loading.

To make matters worse, the research found that the experience shoppers have on a retail site colours their entire view of the company behind it.

About 30% of those responding said they formed a "negative perception" of a company with a badly put-together site or would tell their family and friends about their experiences.

Further research by Akamai found that almost half of the online stores in the list of the top 500 US shopping sites take longer than the four-second threshold to finish loading.

The survey questioned 1,058 net shoppers during the first six months of 2006.