A slow-loading website can frustrate users and affect search rankings. One common culprit is render-blocking resources, which delay how quickly a page becomes visible. Optimizing these resources can significantly improve loading speed and enhance user experience. Here are some effective ways to remove them.
What are Render-Blocking Resources?
Rendering refers to the process of displaying a website on a screen. When a browser loads a webpage, it encounters various files like CSS and JavaScript that contribute to this process. Some of these files, known as render-blocking resources, must be downloaded, parsed, and executed before the page becomes visible, which can slow down loading times.
Common Render-Blocking Resources
- CSS files (unless they use a media attribute)
- JavaScript files (if not marked with async or defer)
- External resources that are slower to load than your website
- Plugins that add their own CSS and JavaScript dependencies
Why Should You Eliminate Render-Blocking Resources?
1. Faster Page Load Times
- Render-blocking resources, such as CSS and JavaScript files, delay the loading of a webpage.
- Eliminating or optimizing them helps load content faster, improving user experience.
2. Better SEO Rankings
- Google prioritizes fast-loading websites in search rankings.
- Render-blocking resources can slow down your page, negatively impacting your SEO efforts.
- Optimizing these resources can improve your Core Web Vitals score, leading to better rankings.
3. Enhanced User Experience
- Visitors expect quick access to content, and delays caused by render-blocking resources can lead to frustration.
- A smoother experience reduces bounce rates and increases engagement.
4. Improved Mobile Performance
- Mobile devices often have slower network connections compared to desktops.
- Removing render-blocking elements ensures that pages load efficiently across all devices.
5. Boosts Conversion Rates
- Faster-loading pages encourage visitors to stay and interact.
- Studies show that even a one-second delay can reduce conversion rates significantly.
How To Eliminate Render-Blocking Resources
1. Optimize JavaScript Loading
- Defer Attribute: Use <script defer> to load scripts after HTML parsing is complete.
Use <script defer> to load scripts after HTML parsing is complete.
Example: <script src="script.js" defer></script>
- Async Attribute: Use <script async> for non-dependent scripts to load them independently.
Use <script async> for non-dependent scripts to load them independently.
Example: <script src="analytics.js" async></script>
- Lazy Loading: Use the IntersectionObserver API to load scripts only when needed (e.g., chat widgets or videos).
You should place the IntersectionObserver code just before the closing </body> tag in your HTML file or inside a script that runs after the DOM is fully loaded.
<div id="lazy-load-target"></div>
<script>
const observer = new IntersectionObserver(entries => {
if (entries.some(entry => entry.isIntersecting)) {
const script = document.createElement('script');
script.src = 'lazy-script.js';
script.async = true;
document.body.appendChild(script);
observer.disconnect(); // Stop observing after loading
}
});
const target = document.getElementById('lazy-load-target');
if (target) {
observer.observe(target);
}
</script>
Replace placeholders:
Replace 'lazy-script.js' with the actual script URL you want to lazy-load.
Ensure the element with id="lazy-load-target" exists in your HTML (or update the ID if different).
- Minify and Combine Files: Reduce file size and HTTP requests by removing unnecessary characters and merging files.
Example:
Original files (file1.js, file2.js) are combined into a single minified file (combined.min.js).
Use in HTML:
<script src="combined.min.js" defer></script>
2. Optimize CSS
Inline Critical CSS: Browsers wait to show the page until they finish loading the CSS. To make the page appear faster, the important CSS for the part of the page you see first (called "above the fold") should be added directly into the HTML using <style> tags. "Above the fold" means the section of the webpage that’s visible without scrolling, and it’s important to load this part quickly.
<!DOCTYPE html>
<html>
<head>
<style>
/* Critical CSS for above-the-fold content */
body {
font-family: Arial, sans-serif;
background-color: #f4f4f4;
margin: 0;
}
h1 {
color: #333;
}
</style>
</head>
<body>
<h1>Welcome to My Website</h1>
</body>
</html>
Defer Non-Critical CSS: Non-essential styles (e.g., footer or below-the-fold elements) can be deferred using the media="print" attribute and switching it back to all after the page loads.
Example: <link rel="stylesheet" href="non-critical.css" media="print" onload="this.media='all'">
3. Handle Third-Party Scripts
Load third-party scripts (e.g., analytics) using defer or async. Move non-essential scripts to load after the page finishes rendering.
4. Progressive Rendering Techniques
- Use Server-Side Rendering (SSR) or static generation frameworks like Next.js or Gatsby to deliver fully formed HTML.
- Optimize fonts with font-display: swap and lazy-load images with loading="lazy".
5. Using Wordpress Plugin
For websites built on the WordPress platform, several popular plugins can help reduce render-blocking resources and improve website speed.
| Plugin Name | Free/Paid | How It Helps Eliminate Render-Blocking Resources | Best For |
| Autoptimize | Free | Aggregates, minifies, and defers CSS and JavaScript files. It can also inline critical CSS and move scripts to the footer, reducing render-blocking resources and improving load times. | Beginners and advanced users |
| Async JavaScript | Free | Adds async or defer attributes to JavaScript files, allowing the browser to load scripts without blocking the rendering of the page. Works well alongside Autoptimize for even better results. | Users who want more control over JS loading |
| Jetpack Boost | Free | Automatically generates and inlines critical CSS, defers non-essential JavaScript, and implements lazy loading for images. Simple setup with minimal configuration required. | Users who want a quick, easy solution |
| WP Rocket | Paid | Premium plugin with advanced file optimization: minifies and combines CSS/JS, defers JavaScript, and inlines critical CSS. Also offers caching and database optimization for overall speed improvements. | Users seeking a powerful, all-in-one solution |
| Perfmatters | Paid | Allows you to delay JavaScript execution, remove unused CSS, and selectively disable scripts on specific pages. Lightweight and easy to use, with a focus on performance. | Site owners who want advanced control |
| WP Asset CleanUp | Free/Paid | Lets you unload or disable specific CSS and JS files on individual pages or posts, reducing unnecessary render-blocking resources. Pro version offers more advanced features. | Advanced users and developers |
| WP Meteor | Free | Delays the loading of all JavaScript until after the page has rendered, which can significantly improve perceived load speed. Simple to use, but may require testing for compatibility. | Users who want a set-and-forget solution |
| W3 Total Cache | Free | Offers options to minify, defer, and compress CSS and JavaScript files, as well as caching for faster load times. Requires more configuration but is very powerful. | Advanced users and developers |
| WP-Optimize | Free | Minifies and defers CSS/JS, cleans up the database, and offers caching. Helps reduce render-blocking resources and improve overall site performance. | Users looking for a multi-purpose optimizer |
Render-blocking resources will make your website load slowly and affect the user experience. Optimizing CSS and JavaScript, lazy loading, and selecting the right WordPress plugins can help your website load quickly. A quick website translates to better SEO, more satisfied visitors, and increased conversion possibilities.
