Performance Testing with WebPageTest

2 min read

Web page speed is essential for user experience and SEO. One tool for testing web page performance is WebPageTest. In this article, we will discuss WebPageTest, how to use it, and how to interpret the test results.

What is WebPageTest

WebPageTest is a tool for testing web page performance. It allows you to measure page loading time, data transfer speed, network usage, and browser resources and detect possible problems in the page code that may slow down loading.

How does loading time affect user behavior?

Marketing specialists of the analytical platform KISSmetrics conducted a study on the distribution of user attention and came to the following conclusions:

  • If the user cannot interact with a site or application within 6-10 seconds, he will leave.
  • The conversion rate decreases with every second of delay.
  • 10% of people wait until two seconds.

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How does loading speed affect sales and conversion?

  • A one-second delay reduces conversion by 7%. If the site earns $ 100.000 per month, increasing the page loading speed by one second can bring up to $ 7.000 monthly.
  • Mozilla noted 60 million more downloads after speeding up its web page by 2.2 seconds.
  • Amazon has estimated that slowing down loading speed by just one second could cost $1.6 billion annually. 

You may consider testing performance to avoid losses or, conversely, to increase profits from the site or application.

How to use WebPageTest?

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To use WebPageTest, you need to go to the official website of the tool: https://www.webpagetest.org/ 

On the main page, you will see a field for entering the URL of the page you want to test. You can select the server’s location where you’d like to run the test.

After entering the URL and selecting the server, click the “Start Test” button. The test will take a few minutes, and you will receive detailed information about the page’s performance.

Interpretation of test results

WebPageTest provides a lot of data about the page’s performance. Some of the most critical metrics that need to be analyzed are:

  • Page Loading Time is the time it takes to load the entire page. The shorter the time, the better.
  • First Byte: The time it takes for the server to send the first byte of data. The optimal time is less than 200 ms.
  • First Paint: The time it takes to display the first image on the page. The shorter the time, the better.
  • Fully Loaded Time: Loading all the resources on the page entirely takes time. The optimal time is less than 5 seconds.
  • Requests: The number of requests sent to the server to load the page. The smaller this number, the faster the page will load.
  • Bytes In: Page size in bytes. The smaller the pages are, the faster they will load. The optimal page size is less than 1 MB.

In addition to these metrics, WebPageTest provides information about how the page loads in the user’s browser using tools such as Waterfall Chart and Filmstrip View. The Waterfall Chart displays the loading time of each element on the page, including images, CSS files, JavaScript files, etc. Filmstrip View shows how the page is displayed to the user as it loads.

WebPageTest can also compare the performance of two or more pages. This can be helpful when comparing the performance of pages from different site versions or your site’s performance with competitor sites. 

In conclusion, WebPageTest is a powerful tool for testing web page performance. It allows you to get detailed information about page loading time, network usage, and browser resources and detect possible problems in the page code that may slow down its loading. Using WebPageTest can help optimize your website and improve the user experience. More on testing tools here.

Are you eager to learn more about web development? Follow our blog and look forward to the next article.

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