Render-blocking resource
A render-blocking resource is a script or stylesheet that must load before the browser can show the page. Too many of them delay what the visitor sees.
Large CSS files in the head and synchronous scripts are the usual culprits. They push back the moment the page becomes useful.
Deferring non-critical scripts and inlining critical CSS lets the page paint sooner, which helps Core Web Vitals and visitors alike.
A practical example
A synchronous third-party script in the head delays the browser from showing useful content.
A common mistake
Deferring every stylesheet or script without checking dependencies and visual behaviour.
How to check it
Use the network waterfall and lab trace to identify blocking resources. Retest the page after a targeted change.
Related terms
See what is broken on your website
Get a free technical SEO audit. Real checks on your real site, with fixes your developer can act on. No sales call required.
We explain every finding in your audit in plain language, like this.