Study: Load Times For 69% Of Responsive Design Mobile Sites Deemed “Unacceptable”

While many brands are using responsive design to create websites that deliver a consistent experience across multiple platforms and devices, mobile web developer Trilibis found that image-heavy responsive design mobile sites are taking an “unacceptable” time to load.

Evaluating page weight, images and load times for 155 prominent responsive design websites — including, and — Trilibis found 69 percent took four seconds or more to load on a smartphone.

Trilibis revealed only one in five of the sites it analyzed delivered a “good” load time on a smartphone, with 31 percent of the sites taking anywhere from eight to 48-seconds to load.

Responsive Design Website Smartphone Load Times:

Trilibis study - load timesAccording to the study, the slow load times were the result of image-heavy sites.

Trilibis claims a site’s load time becomes unacceptable if a page weight goes beyond 1MB. Of the 155 sites analyzed in the Trilibis study, 61 percent delivered a home page at least 1MB in size, where images accounted for, on average, 50 to 60 percent of the site’s page weight. From the study:

While a number of factors can determine the overall weight (i.e., size in bytes) of a web page, images are generally the principle contributor. This is particularly true for responsive websites, which generally serve the same content to all devices. This can lead to overly large images being served to mobile devices.

Image Weight a Key Driver of Overall Page Weight:

Trilibis study - image weight and overall page weightThe study listed the mean load time of the 155 responsive design sites at 7.95 seconds, with a median time of 5.82 seconds. Of all the responsive design websites evaluated by Trilibis, the fastest load time recorded was .54 seconds; the slowest site took 48.08 seconds to load.

In an effort to reduce the page weight of the sites, and load times, Trilibis experimented with the 64 sites whose homepage weight exceeded 1MB. By optimizing every image on each of the sites for all devices, Trilibis was able to minimize page weight on smartphones by 77 percent:

Before server-side optimization, the total image weight of all 64 responsive websites was 115MB. The image optimization process dramatically reduced the page weight for every class of device.

Average Page Weight Savings After Optimizing Images:

Trilibis study - optimization results

Related Topics: Channel: Mobile Marketing | Mobile Marketing | Statistics: Mobile Marketing | Top News


About The Author: is Third Door Media's General Assignment Correspondent, and reports on the latest news and updates for Marketing Land and Search Engine Land. From 2009 to 2012, she was an award-winning syndicated columnist for a number of daily newspapers from New York to Texas. With more than ten years of marketing management experience, she has contributed to a variety of traditional and online publications, including,, and Sales and Marketing Management Magazine. Read more of Amy's articles.

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  • Ashutosh R

    Good article! I have read many such articles and it is good to see such which will lead people to think before they jump on responsive site designing. Some people need to get mobile site versions of their site developed instead of going for responsive sites. Considering the page weight and other factors that destroy mobile user experience instead of helping their cause in certain page heavy sites having a lot of rich media, Javascripts etc.

  • Andrea Pernici

    What is missing here is the TTI metrics and above the fold rendering.
    Considering that non-responsive website take more than 10secs to load and 5 to TTI those numbers aren’t so bad.

  • Tom Maslen

    Any website that has loads of heavy images are going to load slowly on a poor connection. What has this to do with mobiles or responsive web design?

  • Ashutosh R

    Because they are not that much resource rich(having lower capabilities) than PC/laptops… In some cases poor connection is not only the culprit. Plus we are supposed to target people having poor connection as well. Meaning as many segments possible…

  • Tom Maslen

    The phone in my pocket is better spec’d than the PC on my desk. There is no correlation between screen size and capability or connection speed. Most people will use their phone at home via WIFI just as much as they use it on the go.

    Saying responsive web design is bad because sites have lots of images is a stupid thing to say. If a site is heavy its because of the amount of content that is added to the it, not the technique used to make it.

    Its not 2007 anymore, devices don’t sit nicely into one of two device types: “mobile” and “not mobile”. People who think this don’t understand what “mobile” is anymore.

  • Martyn Jones

    I agree Tom, responsive design does not equal mobile. So may people make this mistake.

  • Martyn Jones

    Also, what the link doesn’t say is how the tests where carried out. If you’re on a smartphone with weak signal then obviously the load times will be slow.

  • Ashutosh R

    So do you mean today mobile specific website has no logic. Each and every requirement of a site can be handled well with responsive sites(for mobile visitors) be it made on any theme of product or service. People (even big brands) having separate mobile sites version are living in stone age with no logic to support their act of not having responsive site. People having responsive sites are able to properly interact with all kind of mobiles (feature and smart), tabs or other such devices. They are effectively handling user concerns in all kind of OS environment browsers…

  • Tom Maslen

    I would say responsive should be your default but its not the only option. Yes, you could make a separate mobile site but that has loads of issues.

    The first one being that you can’t reliably define what a “mobile” is anymore. Before the iphone when we started making sites/interfaces, we’d start with the device and work out what content to put onto it. Now because the number of devices accessing our content is so diverse we should start with the content instead. Responsive web design is a better technique to allow us to do that.

    Responsive web design isn’t perfect, but its better to make no assumptions about how people are trying to access your site.

  • Tom Maslen

    “big brands) having separate mobile sites version are living in stone age with no logic to support their act of not having responsive site”

    Yes. Big corporations move much slower than normal, plus the biggest issue they will have will be making a new responsive website work with their legacy CMS system.

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