April 16, 2012, 5:10 PM

Amazon is a case study in mobile site performance

Keynote Systems reveals tips based on how Amazon constructs pages.

Lead Photo

The e-retailer's m-commerce site home page.

Amazon.com Inc. has moved into the top three of the Keynote Mobile Commerce Performance Index for the week ending April 15. While Amazon has remained near the top of this 30-retailer list, the last time it was in this lofty company was six weeks ago.

Amazon’s m-commerce site home page loaded on average in 4.91 seconds and did so completely and successfully 99.28% of the time for the week ending April 15, reports mobile and web performance management firm Keynote Systems Inc. That earned it an index score of 945 out of 1,000. It placed third on the index.

Keynote analysts say retailers can learn much from Amazon and its m-commerce site when it comes to managing mobile site performance.

“On the positive side, Amazon.com uses only one redirect for its mobile home page, containing only two domains, one a Cascading Style Sheet and one in JavaScript,” says Herman Ng, mobile performance evangelist at Keynote Systems. “For smartphones, its mobile home page contains only seven page objects and it uses Cascading Style Sheet sprites to deliver multiple images together. All this make their mobile page very light and efficient for downloading to smartphones.”

A sprite is a web site management tool stemming from Cascading Style Sheets, or CSS, HTML-based templates that define where various objects, such as images or text boxes, appear on a web page. A web designer places multiple images within a sprite so that instead of making multiple web server requests for each image, a device only makes one server request for the sprite, which then passes the images to the style sheets for placement.

But even in its high spot on the index, there are areas where Amazon.com can improve its m-commerce site performance, Ng says.

“Amazon.com does not use CSS sprites for BlackBerry devices, thus increasing the total page elements to 12,” he explains. “Amazon.com also did not use any embedded objects in its HTML base page, which they could do for some of the images. By using embedded objects, Amazon could reduce the total number of network requests required by at least three and its average page load time could easily be reduced by anywhere between one to three seconds.”

An HTML base page is the foundation upon which a site is built.

Amazon.com, No. 1 in the Internet Retailer Mobile Commerce Top 300, did not immediately respond to a request for comment.

Sears Holdings Corp. came in first with a load time of 3.19 seconds and a success rate of 99.49% for a score of 983. Office Depot Inc. came in second with a load time of 4.22 seconds and a success rate of 99.68% for a score of 973. The index average load time was 10.84 seconds, the average success rate was 98.25% and the average score was 784.

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 1-800-Flowers.com Inc., 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.

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