What is Total Blocking Time (TBT)?

We already know the importance of a website’s load time in SEO and user experience. So, I recommend all webmasters to have a regular check of page speed and load time to make sure everything is fine on their website. If you are checking the performance metric of your website, you will see the term “Total Blocking Time” in the report. Total Blocking Time (TBT) was introduced in 2020 and is now an important factor. In this article, I will explain Total Blocking Time and will tell you its importance of it. I will also tell you how to improve Total Blocking Time to improve user experience.

What is Total Blocking Time?

Total Blocking Time (TBT) is a web performance metric that measures the amount of time a web page spends being blocked by long-running JavaScript tasks. It is basically the amount of time when the main thread was blocked between First Contentful Paint (FCP) and Time To Interactive (TTI).

TBT is a more accurate indicator of a website’s performance than other metrics like First Contentful Paint (FCP) or Time to Interactive (TTI) because it takes into account the impact of JavaScript on the page’s responsiveness.

When a web page has a high TBT, it means that the page is slow to respond to user input and can lead to a poor user experience. Long-running JavaScript tasks can block the main thread of the browser, preventing the page from loading quickly and causing the user to wait for the page to become interactive. This can lead to frustration and abandonment, and can also negatively impact search engine rankings.

How to measure TBT?

The best way to measure the TBT of a web page, you need to run a Lighthouse performance audit on your site. You can use any of these tools:

What is a good TBT score?

If TBT is less than 200ms, it is good. A score between 200-600ms is fine but needs improvement. If the TBT score is more than 600ms, it is considered poor and you should immediately take an action to improve the TBT.

How to fix poor Total Blocking Time?

To ensure that everything is fine with your website’s TBT, you can take the following steps:

  • Use web performance testing tools like Lighthouse or Google PageSpeed Insights to measure your TBT score and identify areas for improvement.
  • Optimize your JavaScript code to reduce its impact on page load times. This can include techniques like code splitting, lazy loading, and reducing the number of requests.
  • Use browser caching to improve the speed of subsequent page loads by storing frequently accessed files locally on the user’s device.
  • Compress and optimize images to reduce their file size and improve page load times.
  • Consider using a content delivery network (CDN) to serve your website’s content from multiple locations, reducing latency and improving overall performance.
  • By following these steps, you can ensure that your website’s Total Blocking Time is minimized and that your users have a fast and responsive experience when browsing your site.

Wrap Up

TBT is an important metric and you need to keep an eye on it to make sure it is good. Google gives Page Experience importance. So, you need to keep checking all of Google’s Core Web Vitals factors regularly. I have written several important articles on SEO, Performance improvements, and affiliate marketing. You should also explore other articles to learn about blogging and online earning.


I am a tech blogger, traveler, and entrepreneur


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