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The retailer uses a mobile developer trick to reduce page requests and speed load time.
For the week ending May 20, HSN Inc. moved up four spots in the Keynote Mobile Performance Index to nab the No. 3 position in the weekly ranking of 30 mobile retailers. The retailer achieved a strong performance by being smart about mobile site design.
HSN’s advance stems from its combined strength in home page availability and performance, says Ken Harker, mobile performance evangelist for Keynote Systems Inc. HSN had fewer page errors this week, and its home page loaded successfully 99.66% of the time in an average in 6.52 seconds.
“HSN follows many of the best practices for mobile site design,” Harker says. The home page for the HSN mobile site has just 10 elements and one of those is an image used for cascading style sheet (CSS) sprites, a tool that many mobile site developers use to help mobile pages load faster, he says.
CSS sprites consolidate many images into a single file so that a smartphone accessing HSN’s mobile home page has fewer files to load and thus fewer page requests. This makes the process of sending data from a web server to a smartphone to build a page much quicker. The use of the sprite is the main reason HSN’s mobile home page requires 10 server requests rather than many more, Harker says.
“HSN is striking a good balance overall, managing the need for image content, with the performance benefit of avoiding extra HTTP (or page) requests,” Harker says.
However, Harker notes that HSN’s mobile home page download size, at just over 70K, could be slightly improved. Two images on the HSN mobile site home page are over 20K each, and are almost always the final assets on the page to finish loading, he says.
HSN did not immediately respond to a request to comment its home page download size.
Sears Holdings Corp. once again topped the index this week with a load time of 3.19 seconds and a success rate of 99.28% for a score of 973. L.L. Bean came in second with a load time of 5.32 seconds and a success rate of 99.45% for a score of 915.
HSN is No. 58 in the Internet Retailer Mobile Commerce Top 300. Sears is No. 21, and L.L. Bean No. 52.
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., Sears Holdings Corp. and Walmart.com, to midsized retailers like Sunglass Hut and Toolfetch.com LLC. Keynote tests the sites in the index every hour Monday through Sunday from 8 a.m. through midnight Eastern time, emulating four different smartphones on four different wireless networks: Apple Inc.’s iPhone 4 on AT&T, the HTC Evo on Sprint, the BlackBerry Curve on T-Mobile 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 Chicago, Dallas, 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.