How to Fix Speed Test Warnings & Improve Core Web Vitals

Page speed is a crucial factor that directly impacts your website’s ranking and the volume of organic traffic you receive. If your site takes too long to load, you’ll feel the impact—big time.

In today’s world, where everyone is busy, patience is in short supply. Will visitors stick around if your page takes a long time to load?

The answer is no. They’ll quickly bounce to another site to find what they need, which will hurt both your conversions and your reputation online. To avoid this, it’s essential to optimize your page speed and deliver content more quickly.

In this article, I’ll show you how to fix standard website speed test warnings from tools like GTmetrix, Pingdom, and Google PageSpeed Insights. You’ll learn how to tackle issues like browser caching, deferring JavaScript parsing, enabling GZIP compression, and more to boost your website load time and improve your Core Web Vitals.

Disclosure: Your support helps keep the site running! We earn a referral fee for some of the services we recommend on this page.

Best Tools to Check Your Website Speed

There are many tools available to check your website speed. Popular among them are,

1. GTmetrix. It will tell you how fast your website loads from 120+ servers across 22 global locations. 

GTmetrix will run more than 40 tests on your URL and show recommendations with relevant files or scripts that slow down your pages.

2. Google PageSpeed Insights. It analyzes your page for both desktop and mobile, reports on metrics like load time, interactivity, and visual stability, and gives suggestions to improve your Core Web Vitals.

3. Pingdom Tools. It offers a fast and easy way to test your website’s load time from different regions. You can know the page size, number of requests, and what assets are slow. They have servers in 7+ locations across five continents

Common Website Speed Test Warnings (+ Solutions)

Do you want to know how to score higher in website speed test tools and boost your page performance?

Let us check the common page speed warnings and learn how to fix them step by step. 

1. Reduce server response time

Do you get a ‘reduce server response time’ warning on Google PageSpeed Insights? We can closely examine the probable reasons for your high server response time and ways to boost your website speed. 

Server response time (Time To First Byte) is the time the browser takes to receive the first byte from the server. It should be under 200 ms. If it takes more time to load the first byte, your website will become damn slow. 

A server’s response time depends on several factors, such as: 

A. Bad hosting

If your hosting provider uses outdated servers and old technologies, it will slow down your website and send it offline frequently. Ensure your website runs on the latest PHP version to make it fast and secure. Otherwise, consider changing your host. 

Our recommended web hosting provider: WPX Hosting

WPX Hosting is a fast and reliable hosting company since 2013. They have high-speed servers to deliver your pages at a blazing-fast speed. A custom, fast CDN is also available to further power up your websites and satisfy the needs of your audience in various global locations.

Their hosting plans start at $8.33/mo with unlimited SSLs, unlimited migrations, malware removal, and many other premium quality features. 

You can also consider: GreenGeeks

GreenGeeks is a budget-friendly hosting service for beginners. It is also fast and secure to host any kind of website. They offer unlimited Solid State Driver (SSD) Server storage in all hosting plans, 300% faster than the normal HDD servers.

Their LiteSpeed caching technology will help you to serve pages faster, and a free CDN integration is also available to speed up WordPress again. For $2.95/mo, you can host a single website on GreenGeeks servers. The unlimited hosting costs $5.95/mo with unlimited SSLs, a free domain, daily backups, and other features. 

Choose a fast web host to reduce your server response time and speed up WordPress.

B. Enable Caching

Caching is the process of storing data in a temporary storage so it can be quickly served. It will help you to deliver pages faster to desktop and mobile visitors. 

Our recommended caching plugin: WP Rocket

WP Rocket is the #1 caching plugin for WordPress. It is an all-in-one plugin to cache, database optimization, and lazy load images. I have been using it for over four years and recently extended my license for another 2 years. I shared my experience with WP Rocket in this post. 

WP Rocket can help you remove many warnings from website speed test tools and increase your page speed. 

C. Use a fast CDN

If your hosting provider has no CDN integration, sign up on a fast Content Deliver Network to serve your pages and scripts at maximum speed. It is very important to fix slow-speed issues in the regions where your data center is not located. With a CDN, you can deliver content at the same speed to visitors worldwide. 

D. Image optimization

Un-optimized images could be another reason for your high server response time. Scale and optimize your images to load them faster across devices. 

A fast hosting, caching, and image optimization practices can greatly improve server response time and website performance. 

2. Leverage browser caching

Leverage browser caching is another warning you may get when using website speed test tools like GTmetrix. Let me explain why it occurs on your site first. Then, I will guide you through the multiple methods to remove warnings and speed up WordPress. 

Browser caching is a mechanism to store frequently accessed web resources in the user’s browser. When a visitor enters your website for the first time, it may take some time to load pages, depending on the size of your files. However, for their repeated visits, your page will open quickly as required resources are stored in the local memory of their device. 

If you are getting leverage browser caching warning on GTmetrix, here is an easy way to remove the message for files hosted in your server: Install WP Rocket 

WP Rocket will enable browser caching for desktop and mobile users and fix the warning automatically. It will set an expiry period for different types of files and update your .htaccess file accordingly (otherwise, you should do it manually). But remember that browser caching cannot be applied to files stored on external servers like Google, Facebook, ad scripts, etc.

Any WordPress plugin is helpless in this case. Even though WP Rocket can handle Google Analytics and Facebook Pixel scripts. So you won’t get leverage browser caching warning for them. 

If you are not using caching plugins and want to manually set an expiration time for files, follow these steps.

Open your .htaccess file from the root directory. Click on edit and enter this code for Apache servers,

<IfModule mod_expires.c>
ExpiresActive On
ExpiresByType image/jpg "access plus 1 year"
ExpiresByType image/jpeg "access plus 1 year"
ExpiresByType image/gif "access plus 1 year"
ExpiresByType image/png "access plus 1 year"
ExpiresByType text/css "access plus 1 month"
ExpiresByType application/pdf "access plus 1 month"
ExpiresByType text/x-javascript "access plus 1 month"
ExpiresByType application/x-shockwave-flash "access plus 1 month"
ExpiresByType image/x-icon "access plus 1 year"
ExpiresDefault "access plus 2 days"
</IfModule>

Save the file. 

That’s it. 

3. Minify

Do you want to know how to fix ‘minify JavaScript’ and ‘minify CSS’ warnings on GTMetrix? 

Minification is the process of reducing the number of JavaScript and CSS requests by combining multiple files into one and reducing the file size. Thus, you can considerably improve page loading time and overall website performance.

Minification is an essential feature of all caching plugins like WP Rocket, W3 Total Cache, etc

On WP Rocket, open the File optimization menu to minify and combine CSS and JavaScript files. Save changes and clear cache. 

Minification helps you to get a high score in website speed test tools and reduces your page loading time. 

4. Eliminate Render-Blocking Resources

Eliminate Render-Blocking Resources or defer parsing of JavaScript is another warning you may want to fix on website speed test tools. 

Do you know what it means? Every website contains a variety of JavaScript and CSS codes to load themes and plugins smoothly. They are the basis of a webpage, and when you enter a URL, the browser loads those resources before rendering the HTML part. Hence, they are known as render-blocking resources. 

There are two types of resources – critical and non-critical resources. You can defer non-critical resources with async or defer attributes. But you can’t handle critical resources in the same way as it may break down your website. So you should inline them within the HTML page using <script> and <style> tags. 

Solution: Install WP Rocket

Install WP Rocket on your WordPress website first. Open settings > WP Rocket and visit the File Optimization tab. 

Scroll down to the bottom to locate JavaScript file settings,

Enable the ‘Load JavaScript deferred’ option to defer scripts and remove and eliminate render-blocking warnings from page speed test tools. Scroll down and select ‘Delay JavaScript Execution’ to delay JavaScript files until user interactions like mouse clicks, scrolling, etc.

Sometimes, this option may affect the performance of certain themes and plugins. If so, you can exclude them to ensure they are loading as expected. Expand the Themes/Plugins/Analytics & Ads drop-down box and select relevant tools to exclude.

Save changes.

​You can also consider: W3 Total Cache

Install W3 Total Cache on your website and open Performance > General settings. Locate Minify settings. 

Enable the Minify option first. Change minify mode to manual.

Save settings. 

Go to GTmetrix or Google PageSpeed Insights and collect scripts you want to minify. 

Copy file URLs one by one and go back to the WordPress dashboard. Visit Performance > Minify section. 

Scroll down to JS minify settings. Find the first option,’ Before </head>……….’ and Choose Non-blocking using defer from the embed type drop-down box.

Under JS file management, click on the Add a script button and enter the scripts you copied from the speed test tools.

Save settings & Purge caches.

For CSS files, head to the next section- CSS. 

Click on the ‘Add a style sheet’ button and enter CSS file URLs one after another to minify. Save settings and purge caches. 

Visit Google PageSpeed Insights and test your website again. It should remove the warning relating to eliminating render-blocking resources. 

5. Reduce unused CSS/JavaScript

When you test your website on tools like Google PageSpeed Insights or GTmetrix, you might see a warning that says “Reduce unused CSS/JavaScript.”

This means your site is loading extra code — styles (CSS) or scripts (JavaScript) — that aren’t needed to show the content users first see on the screen.

For example:

• A theme or plugin might load CSS for a contact form on every page, even though the form appears only on the contact page.
• Or a slider plugin might load JavaScript on pages where no slider exists.

All this unused code still needs to be downloaded before your page can load fully. It makes your site slower and affects your Core Web Vitals, especially First Contentful Paint (FCP) and Largest Contentful Paint (LCP).

Speed test tools flag these files because removing or delaying them can improve your website’s load time.

Solution: WP Rocket

How to fix unused CSS

• Head to WP Rocket → File Optimization.
• Under the CSS Files section find the option labelled Remove Unused CSS (Beta) and enable it.
• Optionally also enable Optimize CSS delivery (this helps reduce render-blocking CSS).
• After enabling, clear your site cache and let WP Rocket generate the “Used CSS” for your pages. The plugin will process your pages asynchronously.
• If you make any design or plugin changes, clear the “Used CSS” so WP Rocket rebuilds it.
• Use the CSS Safelist (in WP Rocket settings) to ensure essential styles that trigger issues are excluded from removal.

How to reduce unused JavaScript

• Open WP Rocket, under File Optimization go to the JS section.
• Enable Delay JavaScript Execution. This doesn’t fully remove unused JS but pushes it to load later so it doesn’t trigger the warning.
• Review which JS files are being delayed and make sure you don’t delay scripts needed immediately (above-the-fold functionality).
• Clear cache and retest your site in PageSpeed / Lighthouse after changes.

You can also consider: W3 Total Cache

How to reduce unused CSS / modify CSS delivery

• To specifically target unused CSS: W3 Total Cache Pro offers a feature “Eliminate render-blocking CSS by moving it to the HTTP body”. This helps reduce CSS flagged as unused or render-blocking.

How to target unused JavaScript

• In the JS section of Minify settings, set embedding method such as “Non-blocking using defer” or “Async” (if your site supports it) to reduce the impact of JS flagged as unused.

6. Enable GZIP compression

Are you getting GZIP related warnings on website speed test tools? It will be ‘Enable GZIP compression’ on GTMetrix and ‘Compress components with gzip’ on Pingdom. You can easily fix the warning by updating your .htaccess file or installing WP Rocket. Let us check how it works. 

GZIP compression will help you to reduce the file size and increase the page speed. It supports various file types like HTML, CSS, JavaScript, fonts, XML, etc. 

For Apache servers, you need to add the following code in the .htaccess file to enable compression. 

# GZIP compression for text files: HTML, CSS, JS, Text, XML, fonts

<IfModule mod_deflate.c>

  AddOutputFilterByType DEFLATE application/javascript
  AddOutputFilterByType DEFLATE application/rss+xml
  AddOutputFilterByType DEFLATE application/vnd.ms-fontobject
  AddOutputFilterByType DEFLATE application/x-font
  AddOutputFilterByType DEFLATE application/x-font-opentype
  AddOutputFilterByType DEFLATE application/x-font-otf
  AddOutputFilterByType DEFLATE application/x-font-truetype
  AddOutputFilterByType DEFLATE application/x-font-ttf
  AddOutputFilterByType DEFLATE application/x-javascript
  AddOutputFilterByType DEFLATE application/xhtml+xml
  AddOutputFilterByType DEFLATE application/xml
  AddOutputFilterByType DEFLATE font/opentype
  AddOutputFilterByType DEFLATE font/otf
  AddOutputFilterByType DEFLATE font/ttf
  AddOutputFilterByType DEFLATE image/svg+xml
  AddOutputFilterByType DEFLATE image/x-icon
  AddOutputFilterByType DEFLATE text/css
  AddOutputFilterByType DEFLATE text/html
  AddOutputFilterByType DEFLATE text/javascript
  AddOutputFilterByType DEFLATE text/plain
  AddOutputFilterByType DEFLATE text/xml  

</IfModule>

Save. You have successfully enabled GZIP compression on your website. 

On WP Rocket, you can’t find specific settings for GZIP compression. This is because it is an automated process, and the plugin will add relevant code in your .htaccess file once it is activated. 

7. Optimize images

Are you getting various image-related warnings on website speed test tools? It includes ‘optimize images,’ ‘serve scaled images,’ ‘Serve images in next-gen formats, ‘ ‘ specify image dimensions, ‘ etc. This is because you are not optimizing images properly. 

Compress images to reduce their size and loading time. You can do it with a third-party tool like ShortPixel. 

ShortPixel is a free, lightweight image optimization plugin for WordPress. This will compress files automatically or even in bulk. It supports all popular image formats and serves them in the latest file formats such as WebP and AVIF.

You can use it for free for up to 100 images/month, and their pricing starts at $4.99/mo for 5,000 images. It also allows you to resize images and insert image alt texts automatically to boost SEO.

8. Use a Content Delivery Network (CDN)

Today, almost every hosting company offers a free CDN integration in their hosting plans. It helps you to serve content faster to the end users. If no CDN is available in your plan and you are getting ‘Use a Content Delivery Network’ on GTmetrix, follow any of the solutions mentioned below, 

A. Choose a CDN service

Add a CDN integration to your website. There are several networks available to deliver your resources quickly and smoothly. StackPath is the most popular among them. It is blazing fast and affordable.

Their pricing starts at $10/mo with unlimited sites and 1 TB bandwidth/mo. They have 45 server locations to offer the same speed of content delivery to visitors around the world. 

B. Use Cloudflare CDN

Cloudflare offers a free CDN to run your website fast. Their free plan includes free SSL, 3-page rules, and email support. They also have premium plans to provide advanced features like image optimization, automatic mobile optimization, 100% uptime SLA, etc.

A CDN integration will help you get a green signal from popular website speed test tools and load pages faster on all devices. 

Apply these techniques to fix warnings on website speed test tools and enhance your page performance. Do you have any other queries? Let us know through comments. 

9. High Cumulative Layout Shift (CLS)

“Cumulative Layout Shift (CLS)” is a metric that measures the extent to which the visible content of a page shifts unexpectedly while loading.

In simpler words:

• You open a webpage.
• You start reading or want to click on something.
• Suddenly, the content shifts (text moves down, a banner appears, a button moves).
• That unexpected movement is what contributes to a high CLS score.

A good CLS score is 0.1 or less. Anything much above that (e.g., > 0.25) is considered poor and may indicate that your visitors have a bad experience.

High CLS affects user experience (people end up clicking wrong things or lose their place), and it also impacts SEO since CLS is part of the Core Web Vitals.

Solution: WP Rocket

How to fix High CLS warning using WP Rocket

1. In WP Rocket go to Settings → Media:
   • Enable “Add missing image dimensions” so the browser knows the width & height of images and reserves space.
   • Enable LazyLoad for iframes/videos (with preview image) so heavy media doesn’t shift layout after load.
2. Under Settings → File Optimization:
   • Preload your fonts (helps avoid Flash Of Invisible Text or Flash Of Unstyled Text which can shift layout).
   • Delay JavaScript Execution: For scripts that aren’t needed immediately (especially dynamic content like pop-ups/ads) so they don’t push content when load finishes.
   • Load CSS asynchronously or add critical CSS for above-the-fold content only (but be careful: if done wrongly, it may cause FOOC / layout shifts).
3. Check your ads, embeds, or dynamic content:
   • If you have ads, banners, or iframes that load late – make sure you reserve space (CSS min-height/min-width) so when they appear the rest of the content doesn’t shift.
4. After making changes: Clear WP Rocket cache, then test your page (via Google PageSpeed Insights or GTmetrix) and check CLS score.

10. Serve static assets with an efficient cache policy

When you run a speed test (like Lighthouse or GTmetrix), you may see a warning: “Serve static assets with an efficient cache policy.”

Here’s what it means in simple words:

• Static assets are things like images, CSS files, JavaScript files, and fonts – files that don’t change every time someone visits a page.
• A cache policy instructs the visitor’s browser on how long to retain a copy of the file locally before rechecking with your server.
• If these files aren’t set up to be appropriately cached (or the caching period is too short), then every time a visitor returns or navigates to a new page, the browser must download them again.
• That means slower load times, wasted bandwidth, and a worse experience for repeat visitors.
• The speed tools flag this issue when static resources either lack proper cache headers, such as Cache-Control / Expires, or have a too short “time to live” (TTL) for caching.

In short, to improve your site speed, ensure that your static assets are well-cached for repeat visits.

Solution:

If you have access to your server or hosting settings:

• Identify which assets are flagged in the report (images, CSS, JS, fonts).
• For Apache servers: add the following rules in your .htaccess like:

<IfModule mod_expires.c>
  ExpiresActive On

 # Images
  ExpiresByType image/jpeg "access plus 1 year"
  ExpiresByType image/gif "access plus 1 year"
  ExpiresByType image/png "access plus 1 year"
  ExpiresByType image/webp "access plus 1 year"
  ExpiresByType image/svg+xml "access plus 1 year"
  ExpiresByType image/x-icon "access plus 1 year"

  # Video
  ExpiresByType video/webm "access plus 1 year"
  ExpiresByType video/mp4 "access plus 1 year"
  ExpiresByType video/mpeg "access plus 1 year"

  # Fonts
  ExpiresByType font/ttf "access plus 1 year"
  ExpiresByType font/otf "access plus 1 year"
  ExpiresByType font/woff "access plus 1 year"
  ExpiresByType font/woff2 "access plus 1 year"
  ExpiresByType application/font-woff "access plus 1 year"
  ExpiresByType application/font-woff2 "access plus 1 year"

  # CSS, JavaScript
  ExpiresByType text/css "access plus 1 year"
  ExpiresByType text/javascript "access plus 1 year"
  ExpiresByType application/javascript "access plus 1 year"

  # Others
  ExpiresByType application/pdf "access plus 1 year"
  ExpiresByType image/vnd.microsoft.icon "access plus 1 year"
</IfModule>

If you are using WP Rocket, it automatically adds the needed Expires and Cache-Control headers for static files. W3 Total Cache users can visit Browser Caching settings to set up the expiry headers. Set it as ‘one year’ or 31536000 seconds for CSS/JS/images/fonts.

Finally, clear or purge cache on your caching plugin to reflect changes in Google PageSpeed Insights or GTmetrix or Pingdom tools.

FAQ