What is page load time and why is it important?

With so many sites at their fingertips, today's online shoppers don't have to suffer slow websites. If one of your pages doesn't appear lightning-fast, your customer will move on to speedier online stores-and rather than converting those clicks into sales, you'll have delivered a bad customer experience instead.

In fact, a one-second delay in page load time has been shown to cause a 7 percent loss in conversion and 11 percent fewer page views. For an online store earning $50,000 a day, that one-second delay adds up to more than $1 million in lost sales each year (1).

In its simplest terms, page load time is the average amount of time it takes for a page to show up on your screen. It's calculated from initiation (when you click on a page link or type in a Web address) to completion (when the page is fully loaded in the browser). Usually measured in seconds, page load time is made up of two different parts:

1. Network and Server Time: based on how speedy the internet connection is and how swiftly static assets like photos and other files are served up

2. Browser Time: how long it takes for the browser to parse and execute the document and render the page to make it available for user interaction

The same Web page can easily have different page load times in different browsers (e.g. Safari vs. Internet Explorer), on different platforms (e.g. mobile vs. desktop), and in different locations. If your site is served by one data center in the U.S. but you sell to customers in Australia and the U.K., for instance, those international shoppers are likely to experience much lengthier load times. But if your site's static assets are copied onto different data centers around the world, the page will pull from the data center that's closest to where your shoppers are. That can drastically speed up page load times.

Different pages on the same site can also have radically different load times, because of developer decisions like richer design elements, beefier functionality, and more content on a page. There are several online tools for determining average page load times, meaning it's possible for your Web development team to focus on streamlining your slowest-loading pages first.

Why page load time is important

Search engines like Google use page load time in algorithms that determine search engine rankings, meaning they're more likely to guide shoppers to sites that load quickly (2). Speed isn't the only thing to focus on-there are more than 200 signals in Google's search algorithm, and page load time is just one of them. Even small tweaks can shave time off and help boost your rankings.

Beyond the rankings, optimizing your page load time is a great way to help users get where they're going faster-and happier shoppers are more easily converted into sales. Users who are frustrated by a slow-loading site are likely to "bounce" - that is, visit your store once, leave and never return. The Aberdeen Group found that 40 percent of shoppers abandon a website that takes more than three seconds to load. Loyal customers who slog through a slow experience aren't unaffected either: A one-second delay (or three seconds of waiting) decreases customer satisfaction by 16 percent. Lower satisfaction means your slow-loading pages aren't just impacting that one customer visit-page load time can prevent customers from wanting to return to your site or recommend it to their friends.

1. "'Customers Are Won or Lost in One Second,' Finds New Aberdeen Report"

2. "Using site speed in web search rankings"