Trilibis Web Performance Survey Finds 69 Percent of Responsive Design Websites Fail to Deliver Acceptable Load Times on Mobile Devices
Image size found to be the principle cause of under-performing responsive websites. Use of server-side image optimization can significantly reduce page weight and improve load time on mobile devices.
SAN MATEO, Calif., April 21, 2014
SAN MATEO, Calif., April 21, 2014 /PRNewswire-iReach/ -- A survey published today by Trilibis found that some of the top responsive design websites are delivering unacceptable load times on mobile devices. In an analysis of 155 responsive websites, Trilibis found that only 21 percent of these modern websites were loading in less than four seconds on a smartphone, and that 32 percent of the sites required between 8 and 48 seconds to load.
Trilibis investigated the reason for this sluggish page-load time of responsive sites and found that image size was the primary cause. By analyzing page composition, Trilibis determined that the mean home page weight of the sites in the sample was 1.7MB, with a median weight of 1.2MB. Notably, this figure was considerably heavier than the 420KB average page weight of the top 30 retailers tracked on the Keynote Mobile Commerce Performance Index (i) — a well-regarded industry benchmark.
While a number of factors contribute to the overall weight of a web page, the size of images is often the primary driver. This is particularly true for responsive websites, which are often graphically complex and are designed to deliver an excellent visual experience on all devices. For desktop computers with high-bandwidth connections and abundant local resources (disk, RAM), page weight is not a major concern. But for mobile devices, the exact opposite is true.
When Trilibis examined the relationship between image weight and overall page weight of the sites in the sample, it found that images constituted more than 50 percent of overall page weight for 107 websites (69 percent of the sample). Trilibis found that, on average, images were 50–60 percent of the page weight for these responsive sites, and that load time was unacceptable when overall page weight exceeded 1 MB. In fact, 61 percent of the responsive websites in this sample served a home page of at least 1MB in size.
As part of the survey, Trilibis examined whether server-side processing could lower overall page weight and improve performance on mobile devices. To determine this, Trilibis selected the most image-heavy websites (a total of 64 responsive websites), and performed simple image optimization to reduce images to a size that would ensure excellent rendition of the website on a wide range of desktop and mobile devices.
Before server-side optimization, the total image weight of all 64 responsive websites was 115MB. Trilibis' device detection and image optimization technology dramatically reduced the page weight for every class of device: down to 50MB for desktop browsers, 30MB for tablets, and 27MB for smartphones (a reduction in page weight of 57 percent, 74 percent and 77 percent, respectively).
The mean page weight of the 64 websites was 1.8MB; optimization reduced this to 780KB (desktop), 470KB (tablet) and 420KB (phone). To measure the reduction in load time, Trilibis applied these optimization techniques to three sites in the sample (Boldandnoble.com, Engadget.com and Starbucks.com), and recorded site-load time reductions of several seconds.
"The mobile Web is considerably slower than its wireline counterpart," said Ted Verani, SVP of sales and marketing at Trilibis. "By serving images and pages that are optimized for mobile devices, we see dramatic improvements in page-load time, which translates to a much better overall user experience."
Recommendations for website designers
Carefully managing image size is crucial to ensure responsive websites load quickly and deliver the best experience for mobile users.
Delivering a truly exceptional user experience on the Web requires more than simply redefining layout and styling for the screen width of a particular device. A successful One Web strategy should optimize website assets for specific classes of mobile device.
To optimize performance on mobile devices, consider the use of server-side technologies in conjunction with responsive design techniques. For this survey, Trilibis used SNOW (Software eNabling One Web), its server-side technology that adds automatic device detection and image optimization to responsive websites.
To download the entire survey as a PDF file, click here.
Survey methodology Trilibis compiled a list of 155 prominent responsive sites based on published data from Dashburst, Econsultancy, Mobify, Search Engine Journal, and The Next Web. It examined the total page and image weights of the home page of each of these responsive sites, and then measured the load time of each page on a mobile device. For the image optimization analysis, the JPEG and PNG images of the targeted sites were optimized using image compression and resizing methods so that they were of a size suitable for desktop machines, tablets, and smartphones.
About Trilibis Trilibis develops server-side responsive design technology for businesses, brands and web development firms that need a true "One Web" website architecture. SNOW, the company's core product, makes websites device-aware and enables developers to design high-performance websites that work perfectly on all desktop and mobile browsers, unlocking device-specific features and functionality that make websites mobile-ready, delightful and profitable. Trilibis is a private, venture-backed company located in San Mateo, California. For more information, visit www.trilibis.com or follow @trilibismobile.
Copyright 2014 Trilibis Inc. All rights reserved. Trilibis and SNOW are trademarks of Trilibis Inc. Other trademarks are registered trademarks and the properties of their respective owners.