Think about how you search for things on the web. How quick are you to close a tab and go to the next search engine result if a site takes too long to load? Now consider doing that on your phone while waiting in line for your coffee order–you have even less time, so your expectations for a site to load quickly are even higher.
Web performance is user experience. Fast page load time builds trust in your site; it yields more returning visitors, more users choosing your site over a competitor’s site, and more people trusting your brand. Users expect pages to load in two seconds, and after three seconds, up to 40% of users will abandon your site. Similar results have been noted by major sites like Amazon, who found that 100 milliseconds of additional page load time decreased sales by one percent, and Google, who lost 20% of revenue and traffic due to half a second increase in page load time. Akamai has also reported that 75% of online shoppers who experience an issue such as freezing, crashing, taking too long to load, or having a convoluted checkout process will not buy from that site.
Web performance impacts more than just e-commerce sites; improvements from page speed optimization apply to any kind of site. Users will return to faster sites, evidenced in a study by Google Maps that noted an increase in returning traffic when the Google Maps homepage weight was reduced from 100KB to 80KB. Additionally, page load time is factored into search engine results, bumping faster sites higher in the results list than slower sites.
Page load time also has a significant impact on mobile users’ experience. My team at Etsy found an increased bounce rate of 12% on mobile devices when we added 160KB of images to a page. DoubleClick removed one client-side redirect and saw a 12% increase in click-through rate on mobile devices. In another study, researchers found that if Amazon changed all of their images to compressed JPEG files, it would save 20% of the energy needed to load the page on a phone, and on Facebook it would save 30%.
The bottom line is that your efforts to optimize your site have an effect on the entire experience for your users, including battery life.
These numbers matter because collectively we are designing sites with increasingly rich content–lots of dynamic elements, larger JavaScript files, beautiful animations, complex graphics, etc. You may focus on optimizing design and layout, but those can come at a tradeoff with page speed. Some responsively designed sites are irresponsible with the amount of JavaScript and images they use to reformat a site for smaller screen sizes.
Think about your most recent design. How many different font weights were used? How many images did you use? How large were the image files, and what file formats did you use? How did your design affect the plan for markup and CSS structure?
In this series of posts, we’re going to focus on the basics for optimizing the number and size of requests it takes to load your site quickly. In the next post, we will focus on arguably the biggest quick win for page load time: image formatting and optimization. As you build out sites, sometimes you’ll make choices that favor page load time, other times you’ll make choices that favor aesthetics. The key is to always be thinking in terms of user experience–including performance–and what will have the biggest impact for your site.