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Why does website speed matter?

This is part 1 of Wicked Fast Websites, a three-part series that explores why web performance matters and what you can do about it.

A few year’s ago, Google ran an interesting experiment. They deliberately throttled their search speed, and found that a 500ms delay—that’s just half a second—resulted in a 20-percent decrease in search traffic. Amazon ran a similar experiment, and found that a 100ms delay—just one-tenth of a second—resulted in a 1-percent loss in sales.

In 2009, the average website was 320kb. By 2010, it had doubled to 600kb. At the beginning of 2013, that number had tripled to 1.2mb. As of this month, the average website is now 1.6mb. That’s five times larger than in 2009.

This exponential growth used to not be a problem. We took for granted that both computers and bandwidth got faster and more reliable every year. And then mobile happened.

Mobile WTF!

Photos of the numerous internet-connected devices that exist today

Images by Luke Wroblewski

People are accessing the web from devices with varying levels of computing power and bandwidth. Desktops and laptops, phones and tablets, TVs, watches, video game consoles.

And for a growing number of people, mobile isn’t just one way they access the web—it’s the way they access the web.

A study by Google and Nielsen found that 77-percent of mobile searches happen at home or at work, locations where you would expect someone to have access to a PC. I’m sure you’ve experienced this before. You’re sitting on the couch, comfortable, when you realize you want to look something up. Rather than getting up and walking to whatever room you keep your laptop in, you just pull out the computer you always have with you—your phone—and Google it.

A pie-chart showing the percentage of mobile-mostly/mobile-only internet users in America

Harvard Business Review reported that 55-percent of Americans accessed the internet via a mobile device in 2012. The only surprising thing about that number is how low it is. But that same report also found that almost a third of all Americans used mobile as the primary way they access the internet.

Mobile isn’t just one way people access the web. For a growing number, it’s the only way.

Greater Performance Expectations

Amazingly, despite the varied power and bandwidth of mobile devices, users expect them to be faster than desktops. Almost three-quarters of your visitors—74-percent—will leave your site if it takes more than five seconds to load.

I’ve heard people argue that it doesn’t matter. 4G LTE, they say, is as fast as broadband wifi. And they’re right. LTE is awesome It works great!

Until I go into Target or Home Depot. Or I hit that patch of trees down the street from my house, where I drop phone calls, nevermind get internet. Or when there’s a bad storm, and I still get internet, but it’s not LTE. And that’s here in the United States where we have a fantastic mobile infrastructure.

In developing nations, things are far less predictable, and that’s where mobile growth is really soaring.

Mobile overtakes desktop traffic

In the summer of 2012, India had an important milestone: mobile traffic overtook desktop traffic. China passed a similar milestone at the end of 2012. And in Korea, mobile search queries overtook desktop search queries.

Mobile traffic is surpassing desktop traffic, and not just in developing nations.

A chart showing the growth of mobile traffic over the last two years for

I manage the website for PAWS New England, an all-breed dog rescue. In May of 2013, mobile accounted for 45-percent of all traffic. In 2011, it was just 9-percent of all traffic. While much of the traffic comes from iOS devices, we had one visitor from a Nintendo DS, several from the Nintendo Wii, and an assortment of other (mostly Android-powered) smartphones and tablets.

The Perfect Storm

There’s a myth about mobile users—that they’re always on-the-go and distracted, fleeting consumers of content.

But at PAWS, we’ve found people aren’t just looking at dogs. They’re submitting our (lengthy) application forms and making donations, too. Losing visitors to poor performance means fewer dogs saved and less money to fund our work.

We’re in the middle of a perfect storm. Websites are larger, devices are more varied and less predictable, and performance expectations are higher than ever.

In part 2, I’ll share the tips and techniques I use to build faster websites.