Performance is money, part 1: the end-user’s wallet

Most web developers are familiar with the maxim that light is good: the idea that page performance matters to the end user experience is a truism at this point, backed up by a tremendous amount of real-world evidence, summarised quite nicely at [url=][/url].

But a slow and heavy site doesn’t just hurt the user experience; it can also have a detrimental effect on their wallet. One example stands out in recent memory: a page of the supposedly mobile-friendly site (the [url=]gallery page[/url]) had a total page weight of a staggering 65MB. This page takes many minutes to load when all evidence suggests that users begin to abandon page loads after about 5 seconds.

So, apart from the load time, why does this matter? Well, ever since the launch of the iPhone, most smartphones sold today are bundled with a data plan that covers a reasonable amount of day-to-day usage. For most people and ordinary levels of usage the weight of a particular page is of no concern. This all changes when travelling, however, since very few data plans cover roaming data in their monthly quota. Roaming data is typically charged at a multiple of the basic rate and has a different, lower quota, if any at all. The net effect of all of this is that users get surprisingly high data bills for data activity when abroad i.e. [i]just when you need your phone the most[/i].

We decided to measure just how much this matters. We took a SIM from a European Vodafone account, tied to a contract with a 1GB monthly data quota. We ensured that this SIM was not used for a full month before the experiment. We used the SIM an Android phone while roaming in the USA, loaded a single page (, and then turned off the phone and didn’t use it again until the bill arrived about a month later.

The cost of viewing this [i]single page[/i] was €369 or about $480.


Obviously no real user will be patient enough to wait for this page to load, but many other sites that appear to be mobile-friendly load exactly the same images for desktop and mobile browsers, even though the mobile device typically don’t display images at their full resolution. As [url=]Guy Podjarny[/url] from Akamai has [url=]recently demonstrated[/url], the vast majority of the Responsive Web Design sites listed at RWD directory [url=][/url] don’t vary their page weight for mobile devices: page weights of 2-3 MB are not uncommon.

Vodafone Ireland charge [url=]$7.96/MB[/url], Vodafone UK charge over [url=]$1/MB[/url] for users roaming in the EU. AT&T charge as much as [url=]$19.97/MB[/url] for roaming data in certain countries. Taking some of the examples from Guy’s [url=]spreadsheet[/url], and using the AT&T roaming tariff, is a peak at really worth $178? Do you really need to visit for $44 or for $65? At $17 is a relative bargain.

For roaming users these page weights are prohibitive for all but the most essential tasks.

By contrast, the leading web brands such as Google and Facebook do an excellent job of paring weight when possible and when necessary. Google’s minimal home page is fully 150 times lighter than the desktop version; for Facebook the figure is 55. This is smart and necessary if you want users to come back to your site regardless of their device type and network connection.

You can test the page weight of sites on different devices using our [url=]Prism[/url] multi-device testing tool e.g. [url=][/url], [url=][/url].

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