Evan Schuman's StorefrontBacktalk

Just how out-of-control does mobile commerce get when you’re creating M-Commerce sites for different smartphones on different carriers? Pretty wild, according to the numbers from a new survey of retail M-Commerce sites by Web-metrics company Gomez. The best sites (Petco, QVC, Nordstrom) perform consistently well; the worst (Levi Strauss, REI, American Eagle Outfitters) always have mediocre availability. But in between, it’s chaotic: Content that shows up in seconds on one phone can take half a minute on another, and a site that’s 99 percent available on one carrier can drop to 89 percent on a different one.

Tuning E-Commerce site performance for multiple browsers is an old problem, of course. But programming is just the beginning of the mobile performance problem. It also depends on smartphone hardware, which varies widely in horsepower, and mobile carriers, whose performance can change dramatically if a user moves literally just a few feet away. That makes the puzzle hugely more complex–at a time when retailers can’t afford to avoid that complexity.

To compile the new benchmarks, Gomez ran tests on 70 M-Commerce sites using the most popular smartphone for each U.S. carrier: the Apple iPhone for AT&T, the Motorola Droid on Verizon, the HTC Hero on Sprint and the HTC Dream on T-Mobile.

The results are disheartening, at least if you’re trying to keep smartphone-wielding customers happy. Average response time for most sites was about 5 seconds for the AT&T iPhone and Sprint HTC Hero, 7 seconds for the Verizon Droid and a whopping 14 seconds for the T-Mobile HTC Dream, which took up to 35 seconds for the slowest site in the survey, Best Buy. (How bad is that? In Gomez’s latest survey of users, almost a third said they would abandon a site that took more than 5 seconds to load.)

And it’s not as simple as AT&T-fast-T-Mobile-slow. Case in point: Moosejaw Mountaineering. The $35 million outdoor apparel and sporting goods retailer’s Web site has the second-worst response time on the AT&T iPhone (only Overstock.com is slower). But on the Verizon Droid, Moosejaw’s site responds almost twice as fast, and shows up in the top 20. On the other hand, Polo Ralph Lauren’s site responds twice as fast on AT&T as it does on Verizon.