Transaction-driven sites such as Amazon and PayPal are increasingly embracing adaptive design in order to deliver their sites on mobile up to 40 percent faster than if they used responsive Web design.

 Speedy delivery times are crucial on mobile phones for many Web sites because users are often on the go and looking to answer an immediate need, such as where is the nearest coffee house. While responsive Web design is an important evolutionary step beyond the m dot sites that were once prevalent, many marketers are now looking toward creating experiences that are even more optimized for mobile and adaptive clearly is gaining steam as a possible solution.

?As people started using responsive, they started noticing the challenges,? said Dritan Suljoti, co-founder and chief product officer at Catchpoint Systems, New York. ?It is not necessarily as optimized as it could be because you are trying to deliver the same HTML, the same scripts, to two devices ? desktop and mobile.

?If I am already doing some optimization on HTML, I can do so more on the server side and now it is even further optimized and it is even faster,? he said.

?I don?t think that everybody has to go adaptive. But I think for an ecommerce site, probably the majority of ecommerce, yes, they would want to go adaptive, just given all the benefits that it has to offer.?

Cross-screen optimization
The top 15 sites using adaptive design, according to recent research by Web performance monitoring service Catchpoint, are Google, Amazon, Bing, Pinterest, CNN, PayPal, Fiverr.com, Hulu.com, Usatoday.com, Wikia.com, Tripadvisor.com, Washingtonpost.com, Ask, Pandora and Answers.com.

The top 15 sites employing responsive Web design are Wordpress, Netflix, Microsoft, SuitSupply, Bootstrap, Indochino, Nokia, Sony, NBCnews.com, Constantcontact.com, Capitalone.com, About, Zillow and Conduit.

With the growth of mobile, marketers are increasingly looking for the best methods to deliver the same content across multiple screens instead of having to build and maintain separate sites for desktop and mobile.

Responsive Web design quickly gained steam over the past couple of years because of how it can help marketers build once for multiple screens.

However, responsive comes with its own set of drawbacks, namely that delivery times on mobile can be fairly slow, which recent data from Catchpoint quantifies. This is why some marketers are embracing adaptive design.

Catchpoint?s research ?which was conducted during May 2014 ? reviewed the top 15 U.S. Web sites running adaptive-designed sites and the top 15 running responsive-designed sites. The results reveal that adaptive sites load 40 percent faster on mobile devices running on wireless carriers.

Performance issues
Sites using adaptive design loaded, on average, in 2.6 seconds while responsive Web design sites took over 4.3 seconds to load and sometimes took as long at 6 seconds. The discrepancy in load times can be attributed to the fact that the responsive Web design sites were over 1.2MB in size while the AWD sites, on average, where 791KB.

For the growing number of ecommerce customers shopping from mobile devices, waiting more than 5 seconds can be enough to convince them to abandon a site and go elsewhere. 

There is a lot of confusion among marketers about the different options available for delivering content across multiple screens, with many looking to responsive because it is the most well known.

According to Catchpoint, responsive Web design refers to a process whereby optimization is done from the browser side. So, the same page is delivered to different devices but, using JavasScript and Cascading Style Sheets, the content is modified so that certain items do not display.

For example, with responsive design, images are scaled down and not resized or eliminated.

Low infrastructure costs
In comparison, adaptive design builds from responsive ? with some modifications taking place on the browser side ? to also enable optimization to occur on the server side.

This enables a lighter site to be delivered to mobile users ? something responsive design cannot do ? which translates to speedier load times.

Basically, adaptive design decides which design elements are necessary based on the screen size and resizes or discards the unnecessary ones.

Despite the results showing faster load times for adaptive design sites, responsive Web design may be sufficient for some marketers.

"If you want to optimize the site to be as fast as possible and at the same time, you want to keep development costs low and infrastructure costs low, then yes, adaptive design probably makes the most sense,? Mr. Suljoti said.

"Does it make sense for every site? Probably not,? he said.

"It depends on what your site has, and what content and what audience are getting. If your site is very text heavy, very few images, very few JavaScripts, probably responsive will still work fine.?

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