PageSpeed Exporter logoPageSpeedExporter
LighthousePerformanceRender-BlockingLCPFCPTutorial

How to Fix Render-Blocking Resources: The Complete Guide

Render-blocking CSS and JavaScript delay First Contentful Paint and LCP on almost every site. Learn how to identify, defer, and eliminate them — with code for Next.js, WordPress, and plain HTML.

PageSpeed Exporter Team··7 min read

Render-blocking resources are stylesheets and scripts in the document that the browser must download and process before it can paint any pixels on screen. They are one of the most common causes of poor First Contentful Paint (FCP) and Largest Contentful Paint (LCP) scores — and fixing them is often the fastest path to a 10–20 point Lighthouse improvement.

This guide explains exactly what render-blocking means, how to find the specific files slowing your site, and how to fix them on any stack.

What Are Render-Blocking Resources?

When the browser parses HTML, it builds the DOM top to bottom. When it encounters a or a