Most mobile pages are not meeting users’ performance expectations, with the rush to embrace responsive Web design partially responsible, according to a new report from Radware.

The report, “2014 State of the Union: Mobile Ecommerce Performance,” reveals that, on the iPhone 5s, the median m-dot page takes 4.8 seconds to load and only 15 percent of full-site pages load in fewer than four seconds, even though the average shopper expects pages to render in less than three seconds. The findings are significant given that the holiday shopping season is quickly approaching and Web traffic from mobile devices is expected to spike.

“Online retailers really struggle with two things,” said Tammy Everts, senior researcher and performance evangelist at Radware. “First, there is consumer demand for really high-resolution images.

“At the same time, you can’t increase image resolution without also increasing image size,” she said. “That’s a really thorny issue that site owners struggle with.

“There is a lack of awareness around this as a performance problem.”

Bad advice
The rush to responsive Web design by some marketers before fully understanding how this will impact the mobile user experience is not likely to solve the problem of poor performance.

As an example of how marketers do not fully understand responsive design, Ms. Everts recounts being at a conference where a representative from a well-known technology company explained that the highest quality images are put into its responsive design site so the browsers can scale the images to the device.

“That is probably the single worst piece of advice I have ever heard in relation to images,” Ms. Everts said.

Load times for m-dot sites on smartphones

It is easy to understand what might be driving this kind of thinking, namely the desire for quality images. However, this strategy does not take into account how long it takes to load big images on mobile.

“If your sole concern is implementing a responsive design to insure that, ultimately when the pages renders, you get a really good looking page, then go ahead,” Ms. Everts said.

“But how many people are you going to lose while that page is rendering?,” she said. “The answer is, according to our data, a lot.

“Most people will bail after four seconds, at least 50 percent will bail after three or four seconds. There is no simple solution to that problem.”

Page weight
The annual report is based on a review of how the top 100 ecommerce sites perform on desktop and mobile.

Key findings from the report include that images comprise 50 percent of the average page’s total weight, yet 35 percent of sites failed to compress images, which could significantly reduce payload and streamline page rendering.

Full site load times on tablets

Additionally, 81 percent of sites automatically serve an m-dot version of the home page to smartphones, 20 percent of m-dot sites do not allow shoppers to access the full site and 8 percent of the top 100 retailers serve a tablet-optimized version of their site to tablets.

Median load times varied across tablets, ranging from 5.7 seconds for the Galaxy Note to 8.1 seconds for the Nexus 7.

Other findings include that many retailers serve the pared-down m-dot site to tablet shoppers, even though these users expect a desktop experience.

Some retailers are choosing to serve up t-dot sites to tablet users, with iOS users somewhat more likely than Android users to receive a t-dot site.

High expectations
With shoppers having high expectations for mobile sites, some retailers could lose sales this holiday season because of slow performance.

“There is just a lot of variation in how sites perform, but the common thread is that most pages are just not meeting users’ expectations,” Ms. Everts said. “Part of the reason for that is just sheer size, page complexity.

“Images are a major issue,” she said. “That is a problem that is not going to go away and if anything, it is going to get worse.”

Final Take
Chantal Tode is senior editor on Mobile Commerce Daily, New York