That was the finding from Web site monitoring company Gomez, whose CTO, Imad Mouline, said it's critical for large retailers to test their online stores early and thoroughly in preparation for the holidays, when these companies do heavy business.
Since consumers are expected to spend less than originally forecast, due to the crumbling economy, online retailers need every shopper they can get and can't afford to lose them to technical problems. "There is more pressure this year than in previous ones because of the economy," Mouline said. "The implications are greater than in years past."
Running an online store that can withstand spikes in traffic is getting tougher because these Web sites are getting more complicated, he said. For example, in the past 12 months, online stores have featured significantly more rich media content, such as photos and videos, as well as more interactive capabilities, he said.
In addition, these stores, more than ever, are made up of multiple components powered by an increasing number of external providers. These can be outsourcers that handle a specific task or partners that interface with the site via mashups, Mouline said.
Adding to the complexity is a new generation of browsers that either have recently been shipped or will be shipped soon from vendors including Microsoft, Mozilla, Google and Apple. The new browsers are significantly different from their predecessors, and online stores need to be adapted for them.
For 25 large online retailers, Gomez measures their sites' ability to complete transactions, from picking a product to paying for it, and found that Victoria's Secret fared particularly badly on Monday. That day, the so-called Cyber Monday, has been seen as a big day for e-commerce following big Thanksgiving weekend shopping sprees at brick-and-mortar stores.
Between 6 a.m. and midnight U.S. Eastern time Monday, the Victoria's Secret Web store had availability of 74.30 percent, meaning that out of every 100 visitors, almost 26 were unable to complete a transaction due to Web site problems, Mouline said. Most issues were centered on the site's shopping cart, which for several hours malfunctioned, not allowing shoppers to place items in it, he said.
Others that had availability problems on Monday included Staples (88.32 percent), Costco (92.45 percent), Dell (95.26 percent) and OfficeMax (96.26 percent).
Any performance degradation is costly to online retailers because every day, shoppers are savvier and have higher expectations for convenience, especially when search engines and comparison shopping sites make it increasingly easy to find the same product elsewhere on the Web, he said.
Limited Brands, the parent company of Victoria's Secret, didn't respond to requests for comment on Monday and Tuesday. A Dell spokesman said Monday that the company hadn't detected any problems with its Web site. Staples, Costco and OfficeMax didn't immediately respond to requests for comment.
In addition to availability, Gomez measures response time, which is the time it takes a Web site to complete all the steps in a purchase transaction. By this measure, the site that fared the worst was that of Williams-Sonoma, with an average response time of 27.43 seconds. It was followed by Target, with 21.16 seconds, and Costco, with 21 seconds.
A Williams-Sonoma spokeswoman said via e-mail on Monday: "We are happy to report that our customers have had no trouble shopping our e-commerce site. Traffic is strong and we have not experienced any delays."
Target and Costco didn't immediately respond to requests for comment.
As a point of comparison, the 25 retail Web sites for which Gomez measures transaction performance had an average response time of 17 seconds and availability of 98.13 percent in October.