General Nutrition Centers Inc. might want to look into giving its mobile commerce site some of the retailer’s nutritional supplements to lose weight. For the week ending June 9, GNC’s m-commerce site home page took an interminable 41.41 seconds to load, mobile and web performance management firm Keynote reports. GNC’s mobile load time was about 18 seconds seven weeks ago. The average load time for the 30 retailers on the Keynote Mobile Commerce Performance Index for the week ending June 9 was 9.60 seconds; the best load time was 2.06 seconds.

“GNC’s mobile home page has put on some weight every week,” says Venkatesh Giri, mobile evangelist at Keynote. “The page fluctuates between 800 kilobytes and 1 megabyte, and it makes 56 unique domain calls to piece together the content, serving 104 objects on the page. This is simply unacceptable. Retailers are aiming to load their mobile home page within five seconds, serving as few as five to 10 objects, and making at the most five unique domain calls, while keeping the page size less than 100 kilobytes. GNC’s mobile site defies all mobile web standards with no performance optimization techniques implemented at all.”

GNC needs to make a number of changes to provide a reasonably good customer experience to its mobile shoppers, Giri says. First, cutting down the number of unique domain calls the home page makes should improve load times because a call to each unique domain name, where mobile page content is stored, requires DNS lookup, which on a wireless network can take between 150-200 milliseconds, Giri says. A DNS lookup links a web site’s alphabetical address, such as Retailer.com, to its lengthy numerical address, which web users never see.

“A few of GNC’s DNS lookups take more than 650 milliseconds, and 21 DNS lookups take between 300-600 milliseconds,” Giri says. “Avoiding DNS lookups cuts load times.”

Reducing the number of page objects, currently a whopping 104, will reduce the number of HTTP server requests required to fetch the objects, such as images, boxes of text and JavaScripts, Giri says. The fewer requests, the lower the load time.

GNC should also consider adopting image-optimization techniques because it serves more than 40 images on the mobile home page, Giri says. Using Data URI and/or CSS Sprites should bring performance improvements, Giri says. Data URI is a scheme of encoding data within a web page that make up page elements such as images or CSS, a mark-up language used to define pages and denote where elements appear on a page. With multiple elements encoded within a page, no extra HTTP server request is made to fetch the embedded elements as opposed to a request for each element. URI stands for universal resource identifier, a string of characters used to identify a web resource such as an image. A sprite is a web programming technique that enables multiple images to be saved as one, thus reducing the number of web server calls required and shaving time off of page loads.

GNC did not respond to a request for comment.

GNC came in dead last on the 30-retailer index with a load time of 41.41 seconds and a success rate of 98.34%. Weighting and then combining load time and success rate gives GNC an index score of 216 out of 1,000.

Amazon.com Inc. topped the index with a load time of 5.97 seconds and a success rate of 99.68% for a score of 950. W.W. Grainger Inc. came in second with a load time of 4.15 seconds and a success rate of 99.46% for a score of 927. And The Home Depot Inc. came in third with a load time of 8.37 seconds and a success rate of 9.57% for a score of 897.

GNC is No. 73 in the Internet Retailer Mobile 400, Amazon No. 1, Grainger No. 76 and Home Depot No. 61.

The index average load time was 9.60 seconds, the average success rate was 98.74% and the average score was 704.

Click here and then click on Keynote Mobile Commerce Performance Index Part 1 and Part 2 to see this week’s complete results for all 30 retailers on the index.

Keynote Systems measures 30 representative m-commerce sites exclusively for Internet Retailer. The sites include merchants in multiple categories and channels, and of multiple sizes, ranging from such giants as Amazon.com Inc. to midsized retailers like Toolfetch.com LLC. Keynote tests the sites in the index every hour Monday through Sunday from 8 a.m. through midnight Eastern time, emulating three different smartphones on three different wireless networks: Apple Inc.’s iPhone 4 on AT&T, the HTC Evo on Sprint and the Droid X on Verizon. The HTC Evo and the Droid X run Google Inc.’s Android operating system. Keynote runs the tests in New York and San Francisco.

Keynote combines a site’s load time and success rate, equally weighted, into a single score. Given that both performance and availability are important, the score reflects the overall quality of the home page; a higher score indicates better performance. Scores also reflect how close sites are to each other in overall quality. The index average score is the midpoint among all the sites’ scores.

Keynote is ranked No. 2 among web performance monitoring firms in Internet Retailer’s Leading Vendors to the Top 1000 E-retailers guide.

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