Render-blocking resources slow down your website by delaying the time it takes for a page to load. These are usually CSS and JavaScript files that prevent the page from displaying until they are fully loaded. When a browser encounters these files, it pauses rendering, which can lead to a slower First Contentful Paint (FCP) and Largest Contentful Paint (LCP). Google considers these Core Web Vitals important ranking factors, meaning slow-loading pages can negatively impact SEO.
A slow site can also drive visitors away. According to Google, 53% of mobile users leave a page if it takes longer than three seconds to load. This means that even if you rank well, a sluggish website can cost you traffic and conversions.
Fixing render-blocking issues makes your site faster, improves user experience, and can help with search rankings. In this guide, you’ll learn what render-blocking resources are, how to identify them, and the best ways to remove them on WordPress or any of the WordPress alternatives.
What are render-blocking resources?
Render-blocking resources are CSS and JavaScript files that stop a page from loading until they are fully processed. When a browser loads a webpage, it first reads the HTML. If it encounters CSS or JavaScript files that are not optimized, it pauses the web page from rendering until those files are fully downloaded and executed. This delay can make a website feel slow, especially on mobile devices or slower internet connections.
Browsers prioritize loading and rendering content that appears above the fold (the part of the page users see first). If CSS or JavaScript files block this loading process first, users may see a blank or partially loaded page for several seconds, which can lead to frustration and high bounce rates.
Common render-blocking elements include:
- External CSS stylesheets (.css files) – These files control the design of your website, including fonts, colors, and layouts. If the browser has to wait for large or poorly optimized CSS files to load, it delays rendering the page content.
- JavaScript files (.js files) that load before the page content – JavaScript can add functionality to your site, but when loaded incorrectly, it can prevent the browser from displaying content until it finishes executing.
- Third-party scripts, such as fonts, analytics, or ads – External resources like Google Fonts, analytics, ad networks, and social media widgets often add extra CSS and JavaScript files, which can contribute to render-blocking issues.
How render-blocking resources affect website speed and SEO
Render-blocking resources delay your First Contentful Paint (FCP) and Largest Contentful Paint (LCP), two important Core Web Vitals. Google uses these metrics to measure site speed, and slow scores can hurt your rankings.
A slow-loading page also leads to higher bounce rates. If users have to wait too long, they might leave before the content appears. Even a one-second delay can reduce conversions by 7%. This means that render-blocking issues not only hurt rankings but can also lead to lost sales and fewer leads.
Fixing these issues improves your site speed, enhances user experience, and can increase your chances of ranking higher in search results.
How to identify render-blocking resources on a WordPress website
Before fixing render-blocking issues, you need to find out which files are slowing down your site. Several tools can help identify these problem areas.
Using Google PageSpeed Insights
Google PageSpeed Insights is a free tool that analyzes your website’s performance and provides specific recommendations.
Steps to analyze performance
- Go to PageSpeed Insights and enter your website URL.
- Click Analyze and wait for the report to generate.
- Scroll down to the Opportunities section.
- Look for the warning “Eliminate render-blocking resources.” This will list CSS and JavaScript files that are delaying page load.
Understanding the “eliminate render-blocking resources” warning
When PageSpeed Insights flags render-blocking resources, it means that certain CSS or JavaScript files are preventing the page from loading efficiently. These files should either be deferred, inlined, or loaded asynchronously to improve speed.
Key things to note:
CSS files – If they are blocking rendering, consider delaying or inlining critical styles.
JavaScript files – If marked as render-blocking, check if they can be deferred or loaded asynchronously.
Third-party scripts – Fonts, analytics, and ads often appear in this list. These should be optimized where possible.
Using GTmetrix and other page speed tools
While PageSpeed Insights is useful, tools like GTmetrix and WebPageTest provide more detailed reports on how resources load.
How GTmetrix and WebPageTest can help pinpoint blocking resources
- GTmetrix – Offers a detailed Waterfall Chart that shows how each resource loads and whether it delays rendering.
- WebPageTest – Runs multiple tests to measure real-world performance and highlight problem areas.
Interpreting waterfall charts for optimization
A waterfall chart in GTmetrix or WebPageTest visualizes how each resource loads.
- Look for CSS and JavaScript files with long load times early in the sequence.
- Identify scripts that block other elements from loading.
- Note third-party scripts that take too long to execute.
If certain files take longer than expected, they may need to be deferred, removed, or optimized.
Methods to eliminate render-blocking resources in WordPress
Once you’ve identified the files causing delays, the next step is to optimize them. There are several ways to eliminate render-blocking resources on WordPress.
Minify and combine CSS and JavaScript
Minification and combination help reduce the size and number of CSS and JavaScript files, making your site load faster.
What minification and combination do
Minification removes unnecessary characters like spaces, comments, and line breaks from CSS and JavaScript files, making them smaller. This speeds up loading times without affecting functionality.
Combination merges multiple CSS and JavaScript files into fewer files. This reduces the number of HTTP requests, which improves load speed.
Recommended plugins
You don’t need to do this manually, several WordPress plugins can handle minification and combination automatically:
- Autoptimize – Minifies and combines CSS and JavaScript, along with optimizing HTML and images.
- WP Rocket – A premium caching plugin that includes minification, combination, and other speed optimizations.
- Fast Velocity Minify – Focuses on minifying and combining CSS and JavaScript files efficiently.
These plugins make it easy to optimize scripts without technical knowledge. However, always test your site after enabling these options, as combining files can sometimes cause styling or functionality issues.
Defer JavaScript loading
JavaScript files can block page rendering if they load too early. Deferring JavaScript allows the browser to load content first, improving site speed.
Difference between async and defer attributes
Async – Loads the script asynchronously while the HTML continues parsing. However, execution happens as soon as it’s downloaded, which can disrupt rendering.
Defer – Loads the script in the background while HTML is parsed but waits until the document is fully loaded before executing. This is the better option for scripts that don’t need to run immediately.
Defer JavaScript easily using plugins
If you prefer a plugin solution, WP Rocket makes it easy to defer JavaScript:
- Go to WP Rocket settings in WordPress.
- Under File Optimization, enable Load JavaScript deferred.
- Save changes and test your site speed.
Other plugins like Autoptimize also offer various JavaScript optimization and deferring options.
Load critical CSS first (above-the-fold optimization)
Some CSS is essential for rendering the visible part of the page (above-the-fold content). Instead of delaying rendering for all styles, loading only the critical CSS first speeds up display times.
What is critical CSS and how it speeds up rendering
Critical CSS contains styles needed for the first visible screen. By inlining this CSS in the <head>, the browser renders content immediately, while non-critical styles load later.
Generating and implementing critical CSS with plugins
Plugins like WP Rocket, Autoptimize, and Critical CSS can generate and apply critical CSS automatically:
- Install WP Rocket and enable Optimize CSS delivery under File Optimization.
- If using Autoptimize, enable Inline and defer CSS in the settings.
- Use online tools like CriticalCSS.com if you prefer a manual approach.
Optimize WordPress themes and plugins
Themes and plugins can load unnecessary scripts that slow down your site.
Removing unnecessary scripts from themes and plugins
Disable unused features – Some themes load sliders, icons, or widgets you don’t use. Remove them in theme settings.
Use Asset Cleanup or Perfmatters – These plugins let you disable scripts per page, preventing unnecessary files from loading site-wide.
Choosing lightweight, performance-optimized themes
Some themes are bloated with extra scripts. Switch to lightweight themes like:
- GeneratePress
- Astra
- Neve
- Kadence
These themes prioritize performance and minimize unnecessary CSS/JS.
Optimize third-party scripts
Third-party scripts (Google Fonts, analytics, ads, etc.) can delay page rendering. Optimizing them helps reduce their impact.
Common third-party scripts that cause blocking
- Google Fonts – Adds extra HTTP requests.
- Google Analytics – Loads externally, slowing initial rendering.
- Ad networks – Load-heavy scripts for tracking and display.
How to delay or load them asynchronously
- Self-host Google Fonts – Use a plugin like OMGF to store fonts locally.
- Defer Google Analytics – Use a tool like Google Tag Manager or add defer to the tracking script.
- Lazy-load ads and social media embeds – WP Rocket and Flying Scripts can delay loading until user interaction(lazy loading).
Optimizing third-party scripts ensures they don’t block content while still providing functionality.
Best WordPress plugins to fix render-blocking resources
Using plugins is the easiest way to eliminate render-blocking CSS and JavaScript on WordPress. Here are the best options:
WP Rocket
WP Rocket is an all-in-one performance optimization plugin that automatically handles render-blocking resources.
- Defer JavaScript – Loads JS files without blocking rendering.
- Optimize CSS delivery – Generates and applies Critical CSS.
- Remove unused CSS – Deletes unnecessary styles to reduce load time.
- Built-in CDN and caching – Further speeds up site performance.
Autoptimize
Autoptimize focuses on optimizing CSS, JavaScript, and HTML to improve page speed.
- Minify and combine CSS/JS – Reduces file size and requests.
- Defer and async JavaScript – Prevents JS from blocking rendering.
- Inline and defer CSS – Ensures Critical CSS loads first.
Asset CleanUp
Asset CleanUp helps remove unnecessary scripts and styles that slow down pages.
- Disable scripts per page/post – Stops unused files from loading site-wide.
- Unload unnecessary CSS/JS – Helps remove bloated theme/plugin assets.
- Combine & minify files – Reduces HTTP requests.
Perfmatters
Perfmatters is a lightweight performance plugin that focuses on reducing bloat.
- Disable unnecessary scripts globally or per page
- Defer or delay JavaScript to improve render speed
- Remove Google Fonts, emojis, and other slow-loading elements
- Works alongside WP Rocket for extra optimization
Most sites will see great results using WP Rocket + Perfmatters or Autoptimize + Asset CleanUp. Try different combinations based on your needs.
Monitoring and testing your changes
Once you’ve optimized your site to eliminate render-blocking resources, it’s important to test and monitor page performance to ensure everything is working correctly.
Re-testing with Google PageSpeed Insights
After applying optimizations, run your site through Google PageSpeed Insights again.
- Look for improvements in First Contentful Paint (FCP) and Largest Contentful Paint (LCP).
- Check if the “Eliminate render-blocking resources” warning has disappeared.
- Review Opportunities and Diagnostics for any remaining performance issues.
If necessary, tweak your settings or try different plugins until you get the best possible scores.
Regular performance monitoring
Site performance can change over time due to theme/plugin updates, new content, or third-party scripts. Set up regular monitoring to catch new issues early.
- Use GTmetrix or WebPageTest to analyze performance periodically.
- Enable performance monitoring in WP Rocket (if using) to track ongoing optimizations.
- Keep an eye on Google Search Console’s Core Web Vitals report for any regressions.
Regular testing ensures that your site stays fast and optimized, providing a better experience for users and improving SEO rankings.
Key takeaways
Eliminating render-blocking resources is essential for improving the speed and overall performance of your WordPress site. By taking steps to address these issues, you enhance the user experience and positively impact your search engine rankings. Here’s a detailed recap of what you should do:
- Identify render-blocking resources: Use tools like Google PageSpeed Insights and GTmetrix to analyze your site and pinpoint CSS and JavaScript files that delay the rendering of your page. These tools will help you identify what’s slowing down your site, allowing you to focus your optimization efforts on the right areas.
- Minify and combine CSS/JavaScript: Reducing the size of your CSS and JavaScript files through minification, and combining them where possible, can significantly cut down the number of HTTP requests needed to load your site. This can dramatically improve page load times.
- Defer JavaScript loading and prioritize Critical CSS: By deferring JavaScript loading, you allow essential page elements to load first, without waiting for non-essential scripts. Similarly, loading Critical CSS—styles that are necessary to display above-the-fold content—first ensures that users see something quickly when they visit your site.
- Use performance plugins: Plugins like WP Rocket, Autoptimize, Asset CleanUp, and Perfmatters offer easy-to-implement solutions to optimize your site. These plugins handle tasks like deferring JavaScript, minifying files, and optimizing CSS delivery automatically, saving you time and effort.
- Monitor your site’s performance: Optimization doesn’t stop after the initial changes. Regularly check your site’s performance using tools like Google PageSpeed Insights, GTmetrix, or WebPageTest to ensure that it continues to run smoothly. Monitoring Core Web Vitals through Google Search Console is also important for identifying any performance regressions.
- Consistently optimize for speed and SEO: Website performance is an ongoing process. Stay proactive with optimization and SEO efforts to keep your site fast and competitive. By maintaining a fast website, you’ll improve user satisfaction, reduce bounce rates, and enhance your rankings on Google.
In summary, eliminating render-blocking javascript and CSS files and resources is an effective way to improve your site’s speed, Core Web Vitals, and SEO. If you’re serious about making performance optimization a part of your routine, don’t forget to keep checking and refining your setup as your site evolves.
If you’re also looking to manage and optimize your content strategy, Strive Calendar can be a great tool. Strive Calendar is an editorial calendar specifically designed for WordPress users, helping you plan, schedule, and track your content efficiently. Whether you’re managing a blog or a full content strategy, Strive Calendar allows you to stay organized and focused on what matters most, producing quality content that drives traffic.
Get started with Strive Calendar today to ensure your content is organized, optimized, and aligned with your performance goals, all while keeping your WordPress site in top shape.