Render blocking requests

According to Google PageSpeed Insights, Render-blocking resources are files like CSS and JavaScript that delay page load because the browser must process them before rendering content.

Requests are blocking the page's initial render, which may delay LCP. Deferring or inlining can move these network requests out of the critical path.

Understanding render blocking requests

Before a browser can display a web page, it first needs to parse the HTML. During this process, whenever it encounters a JavaScript or CSS file, it must pause, fetch the file from the server, and execute it before continuing to render the page. These files are commonly referred to as “render-blocking” because the browser cannot show content until they are fully processed.

This can delay how quickly visitors see your content, sometimes leaving the page blank or incomplete for a few moments, which can impact Core Web Vitals such as Largest Contentful Paint (LCP).

Minimizing or eliminating render-blocking resources helps the page load faster and ensures that content is displayed to users as quickly as possible.

How to improve render blocking requests with WP Rocket

WP Rocket has options that can help with the render-blocking JavaScript and CSS.

• Load JavaScript Deferred: Delays execution of JS until after the page is rendered.

• Delay JavaScript Execution: Postpones non-critical scripts until user interaction.

• Remove Unused CSS: Reduces CSS size and eliminates unnecessary rules.

• Minify JavaScript files: Reduces JavaScript file size so they download and parse faster.

• Minify CSS files: Reduces CSS files for quicker loading, helping the browser render content sooner.

Additional resources

• Use async/defer attributes: For scripts WP Rocket cannot handle. Plugins that can help you: Async JavaScript or Critical CSS for WP.

• Read official guidance and audits: Chrome Dev / PageSpeed guidance: Render-blocking requests.