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Reducing Total Blocking Time in WordPress

When it comes to optimizing your WordPress site, one crucial aspect to consider is the Total Blocking Time (TBT). TBT is a performance metric that measures the total amount of time that a page is blocked, preventing users from interacting with it. A high TBT can lead to a poor user experience, causing visitors to leave your site and potentially affecting your search engine rankings. In this guide, we’ll explore ways to reduce TBT in WordPress, enhancing your site’s performance and user experience.

Understanding Total Blocking Time

Total Blocking Time is a metric that quantifies how long a user has to wait before they can interact with your website. It’s calculated by adding up all the blocking periods between First Contentful Paint (FCP) and Time to Interactive (TTI). A blocking period is any stretch of time where the main thread is blocked for long enough to prevent input responsiveness.

Essentially, TBT measures the total time that a page is “blocked” from responding to user input, like clicks, screen taps, or keyboard presses. It’s a critical metric for understanding how users experience your site, especially in terms of responsiveness and interactivity.

Why Reducing TBT Matters

Reducing TBT is important for a few reasons. First, a high TBT can lead to a frustrating user experience. If your site takes too long to become interactive, users may abandon it in favor of a faster, more responsive site. This can lead to higher bounce rates and lower conversion rates.

Second, TBT is one of the Core Web Vitals that Google uses to measure user experience. As of May 2021, these metrics are part of Google’s ranking algorithm. This means that a high TBT could negatively impact your site’s search engine rankings, making it harder for people to find your site.

How to Reduce TBT in WordPress

Optimize Your JavaScript

One of the main culprits of a high TBT is heavy JavaScript execution. When a browser is executing JavaScript, it can’t respond to user inputs, leading to a higher TBT. To reduce TBT, you’ll want to optimize your JavaScript by deferring unnecessary scripts, minifying your JavaScript files, and removing any unused code.

WordPress plugins like Autoptimize can help with this. Autoptimize can aggregate, minify and cache scripts and styles, inject CSS in the page head by default and can move and defer scripts to the footer. It also minifies the HTML code itself, making your page really lightweight.

Use a Caching Plugin

Caching can significantly improve your TBT. When a user visits your site, a caching plugin can serve up a static version of your page, reducing the amount of time it takes for your page to become interactive. There are many caching plugins available for WordPress, such as WP Super Cache and W3 Total Cache.

These plugins generate static HTML files from your dynamic WordPress blog. After a HTML file is generated, your webserver will serve that file instead of processing the comparatively heavier and more expensive WordPress PHP scripts.

Optimize Your Images

Large, unoptimized images can slow down your site and increase your TBT. To optimize your images, you can compress them, use a CDN to deliver them more quickly, and implement lazy loading so they only load when they’re needed.

Plugins like Smush and EWWW Image Optimizer can automatically optimize your images for you, reducing their file size without losing quality. This can significantly improve your site’s load time and TBT.

Monitoring Your TBT

Once you’ve implemented these strategies, it’s important to monitor your TBT to ensure your efforts are paying off. Tools like Google’s PageSpeed Insights and Lighthouse can provide insights into your TBT and other performance metrics.

Remember, optimizing your site is an ongoing process. Regularly monitoring your TBT and making necessary adjustments is key to maintaining a fast, user-friendly site that ranks well in search engine results.


Reducing Total Blocking Time in WordPress is crucial for improving user experience and boosting your site’s search engine rankings. By optimizing your JavaScript, using a caching plugin, and optimizing your images, you can significantly reduce your TBT and create a faster, more responsive site.

Remember, the key to a successful website is a great user experience. By focusing on performance metrics like TBT, you can ensure your site is not only user-friendly, but also favored by search engines.

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