NorthwesternMutual.com’s clinch on the No. 1 spot on the AppDynamics/Mobile Strategies 360 performance index on 3G only lasted a week, as the financial service website dropped four spots to No. 5 for the week ending Jan. 10.

“Northwestern Mutual dropped from the head of the pack last week to the fifth position this week— somewhat curiously because their page weight and elements loaded barely changed, yet their visually complete time was more than a second slower (8.4 seconds this week vs. 7.3 seconds the previous week), as was their first render time (5.9 seconds vs. 4.6 seconds,” says Peter Kacandes, senior product marketing manager, mobile, web and synthetics, for AppDynamics. Visually complete time is the time it takes for the browser to finish drawing the elements on the home page, and first render time is the time it takes for the browser to start drawing the elements on the home page.

The number of elements loaded onto NorthwesternMutual.com’s home page actually decreased from last week to this week, to 71 elements this week compared to 72 the previous week. However, the weight of the home page increased to 1.61 megabytes from 1.59 megabytes.

On the 4G index, NorthwesternMutual.com remained at its No. 9 spot. Northwestern Mutual did not respond to a request for comment for this article.

Further down on the 3G index, many companies jockeyed for a position, mostly because of minor changes, Kacandes says.

“There is more movement (now) as companies are probably starting to make post-holiday changes to their websites in the New Year,” Kacandes says.

For example, online retailer Newegg Inc.’s site dropped to No. 22 from No. 19 because of a 300-kilobyte page weight addition to the home page, which added to the time it took for the home page to both start and finish loading, Kacandes says. Newegg did not respond to a request for comment.

The exclusive AppDynamics/Mobile Strategies 360 Index tracks key mobile site metrics across a range of sites to calculate a weekly average Speed Score on both 3G and 4G mobile carrier networks. The index represents a snapshot of mobile site performance across industries, including retailers such as HSN.com, insurance companies such as NorthwesternMutual.com and restaurants such as McDonalds.com.

AppDynamics each week measures performance metrics of both 3G and 4G networks for each of the 30 sites in the index to determine each site’s Speed Score.

They include:

First render: The time, (in seconds) it takes until the web browser starts drawing the visual elements of a home page.

Visually complete: The time (in seconds) it takes until the web browser has completed drawing the visual elements of a home page.

Number of elements loaded: The number of resources loaded by a home page.

Complete load: The size of the home page when all data is loaded (in megabytes).

Using these metrics, the index calculates the Speed Score. The Speed Score is a ratio that rewards businesses for displaying more visual content on the mobile home page earlier rather than later. The earlier a mobile site home page looks complete to a consumer, the better the mobile experience for the visitor, even if a few remaining elements are displayed later. A site with a higher ratio of content displayed earlier will have a better Speed Score than a site with the same visually complete time but a longer first render time.

For example, site A may have a visually complete home page load time of three seconds, loading 90% of its content in the first second and the remaining 10% in seconds two and three. Site B may have the same three-second visually complete time, but present zero content in the first two seconds and 100% in the third second. The sites have identical visually complete times, but Site A will be perceived as much faster, and will earn a better Speed Score as a result.

The index displays the average across the 30 mobile sites for each metric as well as the average Speed Score on both 3G and 4G networks for each mobile site.

For the week ended Jan. 10, the average Speed Score for 3G was 9.6 seconds compared to 9.8 seconds a week earlier. The average first render was 6.7 seconds compared to 6.6 seconds a week earlier.

Visually complete average was 15.9 seconds compared to 16.4 seconds the previous week. Average number of elements loaded was 97.0, the same as a week earlier. Average home page weight was 1.8 megabytes, the same as the previous week.

On 4G, the average Speed Score was 5.7 seconds, compared to 5.8 seconds the previous week. The average first render was 3.9 seconds, the same as the previous week.

Visually complete average time was 9.3 seconds compared to 9.5 seconds the previous week. Average number of elements loaded was 96.8 versus, the same as a week earlier. And average home page weight was 1.9 megabytes compared to 2.1 megabytes the previous week.

The index is accompanied by a chart on MobileStrategies360.com that is refreshed weekly to illustrate how each mobile site performs as well as index averages. Click here to access the performance chart for the week ending Jan. 10.

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