12 Ways To Reduce Total Blocking Time In WordPress

12 Ways To Reduce Total Blocking Time In WordPress

Need to reduce your total blocking time in WordPress?

Total blocking time is caused by long tasks (over 50ms) that block the main thread.

For WordPress sites, total blocking time is usually caused by unoptimized JavaScript and CSS (often from plugins, page builders, or third-party code) as well as fonts, animations, and images.

Optimizing JavaScript is a good place to start which you can use defer, delay, and asset unloading plugins to do. But if you want to improve TBT at the source, take a look at your JavaScript files and learn which elements on your site are causing high total blocking time.


1. Find Elements Causing High Blocking Time

GTmetrix Waterfall – brown bars represent blocking time.

Chrome Dev Tools – the Performance tab in Chrome Dev Tools shows total blocking time.

Total Blocking Time - Chrome Dev Tools

Third-Party Code – blocking time of third-party code can be directly measured in PageSpeed Insights. Often, this is from Google Fonts, Analytics, Tag Manager, advertisements, and videos.

Main-Thread Blocking Time

Long Main-Thread Tasks – Google lists “minimize main-thread work” as one of the biggest factors of total blocking time. Find your worst main-thread contributors in PageSpeed Insights.

Avoid long main-thread tasks WordPress

What Is A Good Total Blocking Time?


2. Defer JavaScript

Deferring JavaScript improves total blocking time by eliminating render-blocking resources.

WP Rocket and other cache plugins might let you “load JavaScript deferred” but Autoptimize and Async JavaScript do a better job (they fixed all but one render-blocking resource for me).

Install Autoptimize and enable optimize (and aggregate) CSS and JavaScript code.

Optimize Aggregate JavaScript CSS

Next, install the Async JavaScript plugin, head to the settings, and click “apply defer.”

12 Ways To Reduce Total Blocking Time In WordPress 1



This article was written by Tom Dupuis and originally published on Tom Dupuis.

Disclosure: Some of the links in this post are "affiliate links." This means if you click on the link and purchase the product, We may receive an affiliate commission.

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