Buy.com cracks the top 10 of a weekly mobile performance index

But there’s room for improvement, Keynote Systems says.

Bill Siwicki

Rakuten Buy.com shaved some time off its mobile commerce site home page loads and increased its site availability and cracked the top 10 of the Keynote Mobile Commerce Performance Index, moving up three spots to No. 8.

For the week ending Dec. 9, Buy.com’s m-commerce site home page loaded on average in 6.26 seconds and did so completely and successfully 99.25% of the time, according to the index. Weighting and combining load time and success rate earned Buy.com an index score of 777 out of 1,000. For the week ending Dec. 16, Buy.com had a mobile load time of 5.96 seconds and a success rate of 99.45% for a score of 864. Buy.com is a subsidiary of Japan-based e-commerce company Rakuten Inc.

Buy.com’s performance improved because of fewer timeout errors, where the page loading process is halted because a page is loading too slowly, mobile and web performance management firm Keynote Systems Inc. says. With a 5.96-second load time, Buy.com still has room for improvement, says Ken Harker, mobile performance expert at Keynote Systems.

“The site makes 17 HTTP requests to the server for the home page; Keynote recommends 10 or fewer for fast page load times,” Harker says. An HTTP request occurs when a mobile web browser calls a retailer’s server to request an element of a page. “Overall page weight, 140 kilobytes, is heavier than Keynote recommends, as well.  Depending on the mobile network connection, the number of bytes that need to be sent to the browser can be a performance concern. On 3G mobile network connections, pages weighing 50 kilobytes or less offer the best chance at responsive page load times.”

Buy.com is using a single data URI on the home page to encode a JPG image into the page’s HTML and thus avoid having to make an extra HTTP request to the server for that image, Keynote Systems says. URI stands for universal resource identifier, a string of characters used to identify a web resource such as an image. Data URI is a scheme of encoding data within a web page that make up page elements such as images or Cascading Style Sheets, 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.

“A way that Buy.com could further optimize its use of images is to consider CSS sprites for small images like the menu icon, cart button and search button,” Harker says. “As these images are often used together, a single CSS sprite image that can be cached would be an optimal way to avoid the extra latency of separate image file requests. Buy.com has done very well to become a top 10 site in the Keynote Mobile Commerce Performance Index, especially during the holiday season. Getting from 6-second page load times to 4-second page load times could push a site like Buy.com into the top five.”

Buy.com, No. 30 in the Internet Retailer Mobile 400, says it had a heavier home page to accommodate advertising but that the page is back to being slim and trim.

“Rakuten Buy.com’s mobile home page is considered light by all measures. Its weight is consistent with other top Internet retailers and presently we are ranked eighth overall, beating out eBay,” says Roger Andelin, president and chief technology officer. “Rakuten Buy.com’s home page was augmented, heavier, to be able to fulfill a recent mobile ad service. However you’ll see that it’s back to being fast and efficient. For example, on December 18th at 1:59 p.m. Pacific time, the site was recorded at 47.97 kilobytes with two HTTP requests.”

Andelin does not see the need for CSS sprites, per Keynote’s suggestion, because Buy.com already is using Base64, a data encoding scheme for storing and transferring complex data.

“The home page and the toolbar utilize Base64-encoded images, which is considered by Google and many others to be better than CSS sprites for mobile sites,” Andelin says. “We perform consistent updates to our mobile site in order to take advantage of the latest advancements in mobile development technology. In Q1 of 2013 we will be implementing Cascading Style Sheets 3, which has been cited as a significant improvement on both CSS sprites and Base64.”

Office Depot Inc. topped the index with a load time of 3.23 seconds and a success rate of 99.78% for a score of 986. Barnes & Noble came in second with a load time of 4.78 seconds and a success rate of 99.78% for a score of 952. And Toolfetch.com LLC came in third with a load time of a swift 2.61 seconds and a success rate of 99.45% for a score of 938.

The index average load time was 8.76 seconds, the average success rate was 99.22% and the average score was 759.

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 one another in overall quality. The index average score is the midpoint among all the sites’ scores.


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