It found 75% of the 1,058 people asked would not return to websites that took longer than four seconds to load.
The time it took a site to appear on screen came second to high prices and shipping costs in the list of shoppers' pet-hates, the research revealed.
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.
This is a sobering piece of research and should be a caution to website owners wanting sites that are graphically heavy or use a lot of Flash. We've always suggested that 'less is more' when it comes to web design, and this research tends to support this view.