E-retail sites fatten up, slowing performance

A new Radware report gives partial blame for slow load times to the weight of home pages. Consolidate server requests to speed page loading, Radware says.

Thad Rueter

E-commerce sites have become fatter and slower since 2012, potentially testing the patience of online shoppers, suggests a new study from Radware Ltd.

The median e-commerce page takes 10 seconds to load compared with 6.8 seconds in 2012—a 47% slowdown—the vendor says in its spring 2014 report about e-commerce page speeds and performance.

“Page size is partly to blame,” Radware says in its report. Thanks to images and other features, the average e-commerce home page is 20% bigger than even six months ago, the report says. “For most sites, one of the greatest performance drains is the need to complete dozens of network round-trips to retrieve resources such as style sheets, scripts and images. Each of these resources makes an individual round trip from the user’s browser, which requests the file from the host server, which in turn delivers the file to the browser.”

Radware says the median page in its study contains 99 such resources. Each request can take from 20 to 30 milliseconds to fulfill—“even for sites that use a content delivery network to cache resources closer to end users,” the report says.

The data security vendor, which last year bought Strangeloop Networks Inc., a company that helps e-retailers and other web businesses improve the performance of their sites,  tested load times for the home pages of sites included in the Alexa Retail 500, which ranks sites by traffic . Alexa Retail is a subsidiary of Amazon.com Inc., itself the top dog in the newly released Internet Retailer Top 500 Guide. Radware tested the sites on March 24 via a server located in Dulles, VA, using Google’s Chrome 33 browser via a DSL connection.

The study found that the “time to interact”—that is, how long it takes for a “page’s primary content to load and become usable”—stands at 5.4 second for the median web site. That’s certainly better than the median of 10 seconds for a page to load completely, but Radware says most online shoppers will at least think about leaving a page after waiting for three seconds.

Still, the vendor says, “load time is not always the most meaningful measure of a site’s performance.” Radware uses the example of Fineartamerica.com to drive home that point: the site has a load time of 27.1 seconds, seemingly an eternity in the e-commerce realm, yet a time to interact of 2.3 seconds, which indicates that site “delivers a satisfactory user experience,” the report says.

Among other retailers responding relatively quickly to online shoppers, Amazon had a time to interact of 2.1 seconds, with a load time of 3.9 seconds; Nordstrom Inc. (No 25 in the Top 500), came in at 2.0 seconds and 3.0 seconds, respectively; and The Net-a-Porter Group (No. 102) at 2.0 seconds and 10.6 seconds, respectively.

The report also found that the top 100 sites studied had a median load time of 10.7 seconds, 7% slower than for the 500 sites as a whole.

The Radware report offered the following advice for speeding up e-commerce sites:

• Consolidate JavaScript code and Cascading Style Sheets, or CSS, into “common files that can be shared across multiple pages.”

• Combine multiple images into a “rectilinear grid in one large image,” a move that can reduce requests from the browser to the server, saving time on loading.

• Delay loading content that comes “below the fold”—that is, the part of the e-commerce site a shopper must scroll down to see.


Alexa Retail 500, Amazon.com, e-commerce, Internet Retailer Top 500 Guide, page load times, Radware, server requests, strangeloop networks, web site performance, web site traffic