It's no surprise that accessing the Web is typically slower on a mobile phone than on the desktop. But some mobile sites are slower than others. With that in mind, Web research firm Gomez this month compared the mobile Web performance of more than a dozen large retailers as the holiday shopping season gets underway.

Of the 14 stores tested, Amazon's mobile site loaded the fastest at 2.8 seconds, followed by QVC (2.9), Newegg (3.3), and Overstock and Best Buy (both at about 3.4). Bringing up the rear were Sears (6 seconds), Buy.com (6.2) and Target (7).

The average load time was 4.7 seconds -- 50% slower than that of the top retailers' traditional Web sites.

The same three companies (in the same order) also had the most reliable mobile sites, with each accessible more than 99.5% of the time. Finishing at the bottom were Buy.com (95.5%), Sears (96.3%) and 1-800-Flowers (97.7%). The average uptime rate of 98.7% was a percentage point below the retailers' main sites.

Gomez conducted the test between Nov. 1 and Nov. 15 across different locations and different wireless operators, but all on a Motorola Razr.

"This holiday season will be the first true test of the performance of retailers' mobile sites," said Matt Poepsel, vice president of performance strategies at Gomez, a division of Compuware Corp., in a statement. He added that the wide disparity in results "highlights that many retailers have more work to do to improve their mobile Web performance or risk losing a potential slice of the holiday action."

And people are not necessarily more patient on cell phones. A recent Gomez survey of 1,000 mobile Web users found that they expect sites to load as quickly or more rapidly on handheld devices compared to their home or work computer. Why they would have such high expectations for the mobile Web is unclear.

The same study also revealed that two out of three people have had trouble accessing mobile sites, with slow load times the chief complaint. Eighty-five percent will only retry a mobile Web site twice if it does not work initially, and 40% would likely visit a competitor's site instead.

Had the survey of mobile retail sites been conducted on a smartphone rather than a feature phone like the Razr, the results may have been better. A study by Nielsen Norman Group earlier this year found that people with higher-end devices were more likely to complete mobile Web tasks than those with regular phones.