Definition

Page load time is the time it takes to download and display the entire content of a web page in the browser window (measured in seconds).

Diagram of how page load time works

Overview

Page load time is a web performance metric that directly impacts user engagement and a business’s bottom line. It indicates how long it takes for a page to fully load in the browser after a user clicks a link or makes a request.

There are many different factors that affect page load time. The speed at which a page loads depends on the hosting server, amount of bandwidth in transit, and web page design – as well as the number, type, and weight of elements on the page. Other factors include user location, device, and browser type.

How Page Load Time Works

The “stopwatch” begins when a user makes a request and ends when the entire content of the page is displayed on the requesting browser. Below is a typical request-response cycle with various steps that contribute to page load time:

  1. User enters a URL, submits a form, or clicks on a hyperlink
  2. Browser makes a request to the server through the network
  3. The request is processed by the web server
  4. Web server sends the response back to the browser
  5. Browser starts receiving the requested page (known as time to first byte)
  6. Browser parses, loads, and renders the page content
  7. The entire requested page becomes available on the browser

The Impact of Page Load Time

Websites and web services that load quickly have better engagement and conversation rates. In fact, revenue depends on having pages that load fast. Here are a few case studies that prove this:

  • Google: The search giant found that a half second increase in page load time (from 0.4 to 0.9s) caused a 20% drop in traffic and revenue.
  • Financial Times: This digital news publisher carried out research to try and understand the impact of speed on user engagement and revenue. They found that a 1 second delay in page load time led to a 4.9% drop in the number of articles read, while a 3 second delay had a 7.2% drop. Also, the slower website had lower subscription renewal rates.
  • GQ Magazine: In just one month after reducing page load time from 7 to 1.5 seconds, the number of unique visitors increased from 6 million to 11 million. In addition, the median time spent on the website rose from 5.9 to 7.8 minutes, resulting in a 108% increase in ad interaction rate.

How to Improve Page Load Time

There are many ways to improve this metric, but here are some of the most common:

  • File Compression: Reduces the size of the CSS, HTML, JavaScript, images, and other web elements. (Check out ImageOptim for Mac to compress images).
  • Minification: Optimizes the code by removing unused code, white spaces, comments, etc. (Here are some cool tips/tools you can use to minify JavaScript and CSS.)
  • Reducing redirects: Each time a web page redirects the browser to another server, the user faces an additional time for the request-response cycle to complete. Best to get rid of these if possible.
  • CDN: A content delivery network (CDN) puts content geographically closer to your users so they can receive it quicker.

Conclusion

Websites with low-number page load times perform better on almost all fronts. They rank well in search engines, deliver a more positive user experience, and see higher conversions and revenue.

Because average page weight is on the rise, it’s now more important than ever to continuously focus on improving page load time and performance. Open source tools like the coach can help you do this, as well as paid tools like SOASTA.