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How to Fix Render-Blocking JavaScript and CSS in WordPress

Do you want to eliminate render-blocking JavaScript and CSS in WordPress?

If you test your website on Google PageSpeed insights, then you will likely see a suggestion to eliminate render-blocking scripts and CSS. However, it does not provide any details on how to do that on your WordPress site.

In this article, we’ll show you how to easily fix render-blocking JavaScript and CSS in WordPress to improve your Google PageSpeed score.

How to fix render blocking JavaScript and CSS in WordPress

What is Render-Blocking JavaScript and CSS?

Render blocking JavaScript and CSS are files that prevent a website from displaying a web page before loading these files.

Every WordPress site has a theme and plugins that add JavaScript and CSS files to the front-end of your website. These scripts can increase your site’s page load time, and they can also block rendering of the page.

Render blocking issue highlighted in Google Pagespeed Insights

A user’s browser will have to load those scripts and CSS before loading the rest of the HTML on the page. This means that users on a slower connection will have to wait a few milliseconds more to see the page.

These scripts and stylesheets are referred to as render-blocking JavaScript and CSS.

Website owners who are trying to achieve the Google PageSpeed score of 100 will need to fix this issue to attain that perfect score.

What is Google PageSpeed Score?

Google PageSpeed Insights is a website speed test tool created by Google to help website owners optimize and test their websites. This tool tests your website against Google’s guidelines for speed and offers suggestions to improve your site’s page load time.

It shows you a score based on the number of rules that your site passes. Most websites get somewhere between 50-70. However, some website owners feel compelled to achieve 100 (the highest a page can score).

Do You Really Need the Perfect “100” Google PageSpeed Score?

The purpose of Google PageSpeed insights is to provide you guidelines to improve the speed and performance of your website. You are not required to follow these rules strictly.

Remember that speed is only one of the many website SEO metrics that help Google determine how to rank your site. The reason speed is so important is because it improves user experience on your site.

Better user experience requires a lot more than just speed. You also need to offer useful information, a better user interface, and engaging content with text, images, and videos.

Your goal should be to create a fast website that offers a great user experience.

During the last WPBeginner redesign, we kept our focus on speed as well as improving user experience.

We recommend that you use Google Pagespeed rules as suggestions, and if you can implement them easily without ruining user experience, then that’s great. Otherwise, you should strive to do as much as you can, and then don’t worry about the rest.

Having said that, let’s take a look at what you can do to fix render-blocking JavaScript and CSS in WordPress.

We will cover two methods that will fix the render-blocking JavaScript and CSS in WordPress. You can choose the one that works best for your website.

1. Fix Render Blocking Scripts and CSS with WP Rocket

For this method, we’ll be using the WP Rocket plugin. It is the best WordPress caching plugin on the market and allows you to quickly improve your website performance without any technical skills or complicated set up.

First, you need to install and activate the WP Rocket plugin. For more details, see our step by step guide on how to install a WordPress plugin.

WP Rocket works out of the box, and it will turn on caching with optimal settings for your website. You can learn more about it in our complete guide on how to properly install and set up WP Rocket in WordPress.

By default, it does not turn on JavaScript and CSS optimization options. These optimizations can potentially affect your website’s appearance or some features, which is why the plugin allows you to enable these settings optionally.

To do that, you need to visit Settings » WP Rocket page and then switch to the ‘File Optimization’ tab. From here, scroll to the CSS Files section and check the boxes next to Minify CSS, Combine CSS Files, and Optimize CSS Delivery options.

CSS Optimization settings in WP Rocket

Note: WP Rocket will attempt to minify all your CSS files, combine them, and only load CSS needed for the visible part of your website. This could affect your website’s appearance, so you need to thoroughly test your website on multiple devices and screen sizes.

Next, you need to scroll to the JavaScript Files section. From here, you can check all the options for maximum performance improvement.

JavaScript optimization

You can minify and combine JavaScript files like you did for CSS.

You can also stop WordPress from loading jQuery Migrate file. It is a script that WordPress loads to provide compatibility for plugins and themes using old versions of jQuery.

Most websites don’t need this file, but you would still want to check your website to make sure that removing it does not affect your theme or plugins.

Next, scroll down a little further and check the boxes next to ‘Load JavaScript Defered’ and ‘Safe Mode for jQuery’ options.

Optimize JavaScript delivery

These options delay loading non-essential JavaScripts, and the jQuery safe mode allows you to load jQuery for themes that may use it inline. You can leave this option unchecked if you are certain that your theme does not use inline jQuery anywhere.

Don’t forget to click on the Save Changes button to store your settings.

After that, you may also want to clear cache in WP Rocket before testing your website again with Google Page Speed Insights.

On our test site, we were able to achieve 100% score on Desktop and render-blocking issue was solved in both mobile and desktop scores.

Fixed render-blocking issue to achieve perfect page speed score

2. Fix Render Blocking Scripts and CSS with Autoptimize

For this method, we will be using a separate plugin made specifically for improving delivery of your website’s CSS and JS files. While this plugin gets the job done, it does not have the other powerful features that WP Rocket has.

First thing you need to do is install and activate the Autoptimize plugin. For more details, see our step by step guide on how to install a WordPress plugin.

Upon activation, you need to visit the Settings » Autoptimize page to configure the plugin settings.

First, you need to check the box next to ‘Optimize JavaScript Code’ option under the JavaScript Options block. Make sure that ‘Aggregate JS-files’ option is unchecked.

Optimize JS files in Autoptimize

Next, scroll down to the CSS Options box and check the ‘Optimize CSS Code’ option. Make sure that ‘Aggregate CSS-files’ option is unchecked.

Optimize CSS in Autoptimize

You can now click on the ‘Save Changes and Empty Cache’ button to store your settings.

Go ahead and test your website with the Page Speed Insights tool. On our demo site, we were able to fix the render-blocking issue with these basic settings.

Fixed render blocking issue in WordPress with Autoptimize plugin

If there are still render-blocking scripts, then you need to come back to the plugin’s settings page and review options under both JavaScript and CSS options.

For instance, you can allow the plugin to include inline JS and remove scripts that are excluded by default like seal.js or jquery.js.

Click on the ‘Save changes and Empty Cache’ button to save your changes and empty plugin cache.

Once you are done, go ahead and check your website again with the Page Speed tool.

How does it work?

Autoptimize aggregates all enqueued JavaScript and CSS. After that, it creates minified CSS and JavaScripts files and serves cached copies to your website as async or deferred.

This allows you to fix the render-blocking scripts and styles issue. However, please keep in mind that it can also affect the performance or appearance of your website.

Troubleshooting

Depending on how the plugins and your WordPress theme uses JavaScript and CSS, it could be quite challenging to completely fix all render-blocking JavaScript and CSS issues.

While the above tools can help, your plugins may need certain scripts at a different priority level to work properly. In that case, the above solutions can break the functionality of such plugins, or they could behave unexpectedly.

Google may still show you certain issues like optimizing CSS delivery for above the fold content. WP Rocket allows you to fix that by manually adding Critical CSS required to display the above fold area of your theme.

However, it could be quite difficult to find out what CSS code you will need to display above the fold content.

We hope this article helped you learn how to fix render-blocking JavaScript and CSS in WordPress. You may also want to see our ultimate guide on how to speed up WordPress performance for beginners, and our comparison of the best managed WordPress hosting companies.

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Reader Interactions

79 CommentsLeave a Reply

  1. Hello there, your site and tips have really been helpful. Thank you wpbeginner!

    My AMP says customize JavaScript script not allowed. I have tried using and followed your instructions for autoptimize but it didn’t solve the problem. The amp shows the error is in line 12:10 and 18:2.

    • Glad our article was helpful, for AMP specific questions like that we would recommend reaching out to AMP’s support and they should be able to assist.

      Admin

    • There are likely other tools but these are the current ones we recommend for beginners.

      Admin

  2. For W3 Total cache users
    Dont add jquery Script (/wp-includes/js/jquery/jquery.js?ver=1.12.4-wp) It will work otherwise your site will not load properly.
    Css will not through any error

    If Revolution silder will post an error after it –> go to revslider global settings and turn on Insert scripts in footer.

    • Thanks for sharing some recommendations you’ve found through editing your site.

      Admin

  3. I don’t remember when ever i find myself struck in a difficult position, you are always there to help me when no body is around i don’t know of any best site of wordpress guide than wpbeginners, thank you so much

  4. Great info as always!

    I’m with Siteground so have SG Optimizer on my site. I’ve gone through the settings as much as I understand, but still getting the Eliminate render-blocking resources.

    Can I use Autoptimize as well, or will it clash with SG? Thanks

    • You should be able to use Autoptimize with SG Optimizer but if you have any concerns if you reach out to the plugin’s support they should be able to let you know if there are currently any conflicts between the two :)

      Admin

    • You would need to manually go through the code and set the CSS and JS files to load after the content is added to the page.

      Admin

  5. Hi WP Beginner Team,

    Thanks a lot for sharing such a useful article. Autoptimize is an awesome plugin.

    I was looking for a plugin to boost the speed of my wp blog. After reading this post, I installed and activated “Autoptimize” on my blog. And to my surprise it increased the speed of my blog from 39 to 61 for mobile and 76 to 95 for desktop checked on PageSpeed Insights.

    Thank once again for guiding new bloggers like me.

    • If you use Google Page insights then there is a dropdown arrow which will show you the URLs that are causing the problem with a learn more link for how to find the url without their tool.

      Admin

    • There should be a dropdown arrow and when you click that it should show the links to the files :)

      Admin

  6. Thanks dude, Really appreciate your tutorial. I used Autoptimize Plugin and worked for me really well.

  7. When I use all these plugins suddenly my website go slow down & it shows inappropriate content…
    What Can I Do ?? Please Help

    • Hi Deeksha,

      Both plugins are quite safe. If you are seeing inappropriate content on your website, then please make sure that your website is not hacked. You can disable both plugins at any time.

      Admin

  8. Sir When we install Autoptimize plugin in our WordPress blog then our blog is not opening it says this page is not working. What should I do Sir?

    Sir I would like to know when we add javascript link to eliminate render blocking code following by your steps then any affect is occuring on my blog ranking. please help

    • Sumit:

      The plugin is not working so you need to rename the plugin folder to turn it off. You need ftp or a file manager plugin. Can you access the dashboard via your wp-login.php location? Like domain/wp-login.php

  9. I use wordpress.com, any plugin to do the same thing here on wordpress.com since this plugins are no supported here? Thanks

  10. Autoptimize works for me. it nicely condenses my scripts, bit I do still see the render-blocking script warning

  11. Hello,
    Currently I am using WP Rocket, is it possible to use Autoptimize plugin together? Thanks for sharing this valuable information.

  12. Hi there. I’ve tried the W3 method and as soon as I turn on Minify (using Disk) I get this:
    Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0

    How does one fix that?

    Great tutorial though overall! Thanks for this.

    • EDIT: This problem goes away when I deactivate Autoptimize, however, so does the rest of the site. Only the bare bones remain with no actual content. :|

  13. The settings for Autoptimize has changed. The only JavaScript Options available is Optimise JavaScript Code? The rest of the options in your screenshot is not available, at least not on the one I have. Last time I tried W3 Total Cache, nobody could access the site. I am still looking for a way of solving the load time of the page, which for some reason stand at anything from 10 – 17 seconds.

    • David, try Gmetrix web speed tool. On the results list there is a waterfall chart showing how the site loads and what the largest files and scripts slowing the page load.
      I find the slowest scripts are googles cdn scripts like google fonts! The very same company insisting, forcing users to their demands have to scripts taking an age to load. You couldn’t make it up.

  14. Can you use minify on w3 total cache simultaneously with cloudflare? We are using minify in cloudflare and left it disabled in w3cache. But we still keep getting the message- Eliminate render-blocking JavaScript and CSS in above-the-fold content.

    Thanks!

  15. The plugin 23 cache UI has been changed and it doesn’t have any option where we can put our .js URL for optmization.
    I am talking about “Now head over to your WordPress admin area and go to Performance » Minify page.”

  16. Great tutorial. However is W3 Total cache safe to use now due to an issue earlier in the year? I’ve stopped using it since but it was the best plugin out there.

  17. Thanks for sharing this article but you said (please keep in mind that it can also affect the performance or appearance of your website)
    Please clarify if this effect will be good or bad for the website google ranking?

    • Hi Mohamed,

      A faster website is certainly good for SEO rankings. However, when fixing render blocking issues you may end up changing appearance of your theme or get even a lower page speed score than before.

      Admin

  18. Ha, funny.

    I was looking for help here.
    then I did the google speed tool for YOUR post here.

    Google result

    mobile Poor
    54 / 100

    desktop
    Needs Work
    66 / 100

    Do you have any clue at all?

  19. Every single time I use Autoptimize or W# Total Cache my site explodes. The mobile web view gets trashed into an html menu list and parts of the site stop working. I have tried each of these on 4 different sites and dropped both of them.

    • Chris I suggest you read and adhere to the W3 Cache warning on the minify section. Minify html and css only and again be wary not all css should be mini-fied due to the reasons stated in the post above.
      I use W3 Cache selectively, tinyjpg for image optimisation, and set OpCache in the .htaccess file. Templaters love to use Sliders…but they bloat the page with images screen width at 1920pxs. Ditch the sliders, smaller images (with a modal box if greater detail required) and icons instead.

  20. I just installed and it broke my homepage. All the images are gone.

    Any idea how to fix this?

  21. Hey guys! I’ve loved the W3 tutorial. There’s just one information missing: The Embed Location for the JS File Management.

    Is it “Embed before Body”? Or “embed in Head”? Or “Embed after Body”?

  22. I am new to Blogging, however, I have been following Wpbeginner.com for quite sometime and whatever they are writing I found them very useful and don’t hesitate to say that, today if my blog page is Live…30% credit goes to Wpbeginner.com team and Sayed Balkhi for creating such a wonderful and useful webpage.
    I am thankful to Wpbeginner.
    Keep it up, all the best.

  23. Plugins increase loads on our website which makes our site slow. At wpbeginner, I haven’t seen a single method of speed optimization without the use of plugins. Teach us something useful, these methods don’t work for everyone.

  24. Great detailed information on using Autoptimize plugin dealing with Java-scrip, CSS and plugin w3 Total Cashe to fix render blocking while enhancing website speed performance

  25. Thanks a lot for this information. Earlier my page loading load time speed was 63 and after installing Autoptimize plugin it increases to 81.

    • I am not very sure what happen, I installed autoptimize in one of my site, then the page size increase from 2.8mb to 4mb

  26. Thanks for sharing.
    Overall the speed of the site increased by very little. But the issue with render blocking is not resolved.

    Comment if you have other suggestions.

    thanks.

  27. I got 3 new websites down to almost 500 ms, faster than 96% of sites on Pingdom. Similar for other speed testers.

    Thought great, till Google brought me back down to earth with their page insights. Mainly low score for mobile, but thought these modern themes are meant to be responsive? Obviously not!

    I squeezed every image down to next to nothing before uploading as well, so it is frustrating.

    Also, none of the apps work for me with Browser Cache, etc.

    I’d say the same three problems I have – once the basics are done – are:
    1. Render blocking Javascript.
    2. Browser caching.
    3. Images wrong size for mobile.

  28. I’m a bit confused. I just ran a Google speed test on wpbeginner and if didn’t score well at at all. What am I missing?

  29. My Website is an RTL one after i saved the settings of the “Autoptimize” plugin my website turn into LTR !

  30. Both Autoptimize and W3 Total cache plugins have damaged my website. These plugins works with certain themes only. One has to be very careful to use these two plugins.

  31. When I installed Autoptimize, as suggested in this article, it completely screwed up my website. Maybe I set it up wrong, but after removing it entirely, I reached a Google PageSpeed score of 92 for desktop. Mobile is at 67, so I’m working on improving that, but won’t be using Autoptimize again, that’s for sure!

  32. Hi WP beginner,

    Very helpful article!
    Thank you!

    Just a random question?

    Can I set it back minified mode from manual to auto and delete the minified files without harm? And what do you recommend: manual or auto?

    Cheers

  33. Hi i Liked article butt em not getting option to add scripts in W3 Total cache plugin kindly let me know how to get that?

  34. Thank you very much for your great article, it’s really helped me.
    Just i have an small problem, i’m confused now!
    I added all .js and .css manually on W3TC, but still one .css has problem on google page checker:

    Consider Fixing:

    None of the above-the-fold content on your page could be rendered without waiting for the following resources to load. Try to defer or asynchronously load blocking resources, or inline the critical portions of those resources directly in the HTML.

    Optimize CSS Delivery of the following:

    26952.default.include.c9d602.css is available currently on .css list, but i see this error. How can i fix this problem?

  35. Ok I did the steps and installed W3 & went thru the total beginners guide. I also added the edge on W3 although it is in beta and went back and changed from embed the JS before the /body to embed the JS in the head. I now have my desktop speed at 75 (was at 69). And mobile is at 50 (was at 38). Google speed is still saying I need to minify, etc etc. Any other hints or tips or plugins?? Thanks for the help so far

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