CSS & Rendering · AuditJet Glossary
Render-Blocking Resources
CSS and JavaScript files that prevent the browser from rendering any page content until they have been downloaded and processed.
By default, <link rel=stylesheet> and <script> tags without async or defer block the browser's HTML parsing and rendering. Render-blocking resources delay FCP and LCP because the browser waits for them before showing any content. Fixing render-blocking issues involves inlining critical CSS, deferring non-critical CSS, and adding async or defer to non-critical scripts.
Related terms
The time from page navigation start until any text, image, non-white canvas, or SVG is first rendered on the page.
The time from page navigation start until the largest image or text block visible in the viewport has finished rendering.
The minimal set of CSS required to render the above-the-fold content of a page without loading any external stylesheet.
Frequently asked questions
What is Render-Blocking Resources?
CSS and JavaScript files that prevent the browser from rendering any page content until they have been downloaded and processed.
How does AuditJet measure Render-Blocking Resources?
AuditJet runs automated Google Lighthouse audits that surface Render-Blocking Resources scores alongside actionable fix guidance. You can track Render-Blocking Resources trends across all your pages and receive alerts when the metric regresses.
Monitor Render-Blocking continuously
AuditJet tracks Core Web Vitals on a schedule with revenue impact alerts — powered by Google Lighthouse and Google PageSpeed Insights.
Start Free