Core Web Vitals: how to make your website fast, user-friendly, and visible on Google

Google Core Web Vitals are indicators that help to assess how fast a website loads, how quickly it responds to user actions, and whether content is displaced during loading. They affect how user-friendly a website seems to people, and Google takes them into account when determining search rankings. The algorithm started working in June 2021 for mobile sites, and in February 2022, it began to affect desktop versions as well.

The main indicators of Core Web Vitals are:

• Largest Contentful Paint (LCP) is the time it takes to load the largest element on a page (for example, a large image or headline). For a website to work quickly, this indicator should be less than 2.5 seconds.
• First Input Delay (FID) - how much time passes between the user's action (pressing a button, making a choice in a menu) and the site's response. A good indicator is less than 100 ms.
• Cumulative Layout Shift (CLS) - how much the content shifts when the page loads. For users to feel comfortable, the value should not exceed 0.1.

Why are Core Web Vitals important for websites?

Better user experience (UX). If a website loads quickly and doesn't “jump” while browsing, it is much more convenient for users to use it. This is especially important for mobile devices - a fast and stable website retains visitors longer.

Influence on SEO. Google has confirmed that these indicators are taken into account when ranking websites. If your site is faster than competitors with the same content, it can rise higher in search results.

Increase in conversions. Even a minimal acceleration of page loading (for example, by 0.1 seconds) can significantly increase the number of orders, applications, or subscriptions. People just don't like to wait!

How to improve Core Web Vitals scores?

1. Optimize Largest Contentful Paint (LCP):

• Reduce server response time (connect a CDN, use a fast and already optimized platform or CMS for your site, such as Solomono).
• Optimize image loading (use WebP or AVIF formats).
• Provide priority loading of CSS and fonts.

2. Reduce First Input Delay (FID):

• Minimize the use of heavy JavaScript.
• Use the Code Splitting technique.
• Optimize the execution time of the main JavaScript threads.

3. Cumulative Layout Shift (CLS) improvements:

• Specify the exact dimensions for images and videos.
•  Avoid inserting new elements without predefined space.

Core Web Vitals analysis tools

For testing, we took our client's online store. To understand the scale, the site offers more than 15 thousand products.

Google PageSpeed Insights. Analyzes page loading speed and provides recommendations for improvement.

How to use:

• Go to PageSpeed Insights.
• Enter your page URL and click Analyze.

What you can see:

• Core Web Vitals metrics (LCP, FID, CLS).
• Separate data for mobile and desktop versions.
• Real user data (Field Data) and simulated data (Lab Data).

Google Search Console (Core Web Vitals report). Provides real user data (Field Data) about all pages of your site.

How to use:

• Sign in to Google Search Console.
• Open the Core Web Vitals section in the Enhancements menu.

What you can see:

• Pages that are marked as “good,” “needs improvement,” or “poor.”
• LCP, FID, and CLS-related issues with URLs.

Lighthouse. A technical audit tool integrated into Chrome DevTools and available as a standalone module.

How to use:

• Open your website in Google Chrome.
• Press F12 (DevTools), go to the Lighthouse tab.
• Select the audit options (mobile or desktop) and click Generate Report.

What you can see:

• Core Web Vitals metrics.
• Recommendations for improving performance, accessibility, and SEO.

Web.dev. A platform from Google that provides access to Lighthouse analysis and learning resources.

 How to use:

• Go to Web.dev.
• Enter your page URL and click Run Audit.

 What you can see:

• Detailed report on performance, SEO, accessibility, and best practices.

Chrome DevTools. Developer tools in the Chrome browser for performance analysis.

How to use:

• Press F12, go to the Performance or Rendering tab.
• Record the interaction with the site or analyze page load metrics.

What you can see:

• Load graphs, JavaScript latency, and element offsets.

How do I interpret the data from the tools correctly?

1. Understanding the indicators:

• LCP (Largest Contentful Paint): A long load time means that the server, fonts, or images need to be optimized.
• FID (First Input Delay): Problems are usually related to JavaScript blocking.
• CLS (Cumulative Layout Shift): Content shifts due to the lack of fixed sizes for images or elements.

2. Field Data vs. Lab Data:

• Field Data: Collected from real users. Reflects the real behavior of the site.
• Lab Data: Uses standardized conditions for testing. It helps to diagnose problems.

3. Grouping pages in Google Search Console:

• Analyze which groups of URLs have problems. This will help you prioritize your tasks.

4. Prioritize tasks:

• Start with the main pages that generate the most traffic.
• Prioritize the mobile version of the site.

5. Tool recommendations:

• Use the step-by-step tips provided by the tools to fix problems. For example, optimize images, reduce the size of JavaScript, and add a delay for unimportant elements.

Analysis of each Core Web Vitals metric

Largest Contentful Paint (LCP)

Let's remind ourselves of the meaning of each metric. LCP measures the load time of the largest visible element on a page, which can be an image, video, or large block of text. This is an indicator of the loading speed of the main content.

Optimal LCP values:

• Good: less than 2.5 seconds.
• Needs improvement: 2.5 to 4 seconds.
• Poor: more than 4 seconds.

The main reasons for poor LCP:

1. Large image size. Images take a long time to load due to a lack of optimization.
2. Slow servers. Delays in server response or lack of caching.
3. Blocking CSS or JavaScript rendering. The page cannot display the main content until JavaScript is executed or CSS is loaded.

How to improve LCP:

1. Image optimization:

• Use modern formats (WebP, AVIF).
• Set up adaptive image loading (srcset).

2. Using CDNs:

•  Place resources closer to users, reducing delivery time.

3. Asynchronous loading of JavaScript and CSS:

• Use async and defer to load scripts.
• Minimize and combine CSS files.

First Input Delay (FID)

FID measures the time between the first user interaction with a website (e.g., clicking a button) and the moment when the page responds to that action.

How is FID measured?

It is measured in milliseconds and characterizes the interactivity of a website.

Optimal FID values:

• Good: less than 100 ms.
• Needs improvement: 100 to 300 ms.
• Poor: more than 300 ms.

Reasons for high FID:

1. High JavaScript load:

• Long script executions block the main thread.

2. Delays in server responses:

• Servers do not provide fast processing of requests.

How to improve FID:

1. Minimize JavaScript:

• Reduce the size of scripts, use tree-shaking.
• Use Code Splitting to load only the necessary code.

2. Use of web developers:

• Move heavy computations from the main thread to web workers.

3. Improve server performance:

• Implement caching, optimize databases.

Cumulative Layout Shift (CLS)

CLS measures how much the elements on a page shift as it loads. This indicator indicates the visual stability of the site.

Optimal CLS values:

• Good: less than 0.1.
• Needs improvement: from 0.1 to 0.25.
• Poor: more than 0.25.

Causes of layout offset:

1. No fixed dimensions for images or videos:

• Elements do not have defined sizes, which causes the page to be rebuilt.

2. Dynamic content that appears without warning:

• For example, banners that are added after the page is loaded.

How to improve CLS:

1. Fixing the size of elements:

• Specify exact dimensions for all images, videos, and ads.

2. Avoid dynamic content changes:

• Reserve space for dynamic elements such as banners or pop-ups.

3. Preload fonts:

• Use the font-display: swap attribute.

Case study: how Core Web Vitals improvements have affected organic traffic.

Case study: E-commerce site with LCP enhancement

Problem: An online store selling car parts had a long page load time (LCP = 4.5 seconds).

Actions:

• Optimized the size of images by converting them to WebP.
• Implemented a CDN to speed up content delivery.
• Reduced server response time by using caching.

Result:

• LCP improved to 1.7 seconds.
• Average position increased by 1.9, comparing the last 28 days to the previous 28 days
• The number of clicks increased by 7400

How can I improve Core Web Vitals for my website?

Improving Core Web Vitals includes technical optimization of the site, the use of modern web technologies, and automation tools. Below are step-by-step recommendations.

Technical aspects

1. Use caching for fast loading
2. Using a ready-made fast CMS

Tools for automation

1. Using Webpack to minimize JavaScript and CSS
2. Integration of Google Tag Manager to optimize third-party scripts
3. Cloudflare to improve performance

How to prepare your online store for Google Web Core Vitals

1. Choose the right image size

Images on your website should be of the optimal size - no larger than necessary to display them. Images that are too large slow down loading, even if they are visually reduced through CSS. The site loads faster, especially on mobile devices.

2. Delay loading images (lazy load)

Images are loaded only when they are in the user's view. Reduces the initial amount of content to load, speeding up the first page load. Improves LCP (Largest Contentful Paint) scores in Core Web Vitals.

3. Reduce the JavaScript file

Optimization and minification of JavaScript code - removing unnecessary stuff. Excessive JS increases page size and browser load, which worsens interaction time. Improve the FID (First Input Delay) indicator.

4. Display images in new formats (WebP)

Use modern formats like WebP, which provide a smaller size without losing quality. WebPs load faster than PNGs or JPEGs. Reducing the overall page size, increasing speed.

5. The server responds quickly

Server response time (Time to First Byte) is how quickly the server responds to a request. Slow server = slow website, regardless of the frontend. Better page loading, especially for new visitors.

6. Preload images to visualize large content

Instructs the browser to load important images (such as a banner or header) before displaying them. Reduces the time to the first large visual element (LCP). The user sees the “main” content faster and improves UX.

Our CMS is ready for Google Web Core Vitals requirements

In 2025, the speed and quality of website loading is not just a technical detail, but a significant factor in Google rankings. That is why our CMS is built with all the key requirements of Core Web Vitals in mind.

What we have already implemented:

• Minification and lazy loading of critical styles (Critical CSS) - provides fast visual display of the page.
• Clean and compressed CSS code - reduces the amount of data transferred to the user.
• Optimal Image Formats (WebP) - lighter files without losing quality.
• CDN (Content Delivery Network) - instant delivery of content regardless of the user's region.

Thanks to these solutions, we achieve PageSpeed results of 98 out of 100.

If you, as a business owner, understand how important it is for SEO, traffic, and user experience, you also understand how much such optimization costs. You can read more about the importance of CWV in the article from Google “Understanding Core Web Vitals and Google search results”.

But you don't need to spend tens of thousands of dollars on technical rebuilding - we've already done it for you. SoloMono is a turnkey solution with out-of-the-box optimization

How do I track my progress in Core Web Vitals?

Tracking your progress in Core Web Vitals helps you evaluate the effectiveness of your optimizations and maintain high performance. For this purpose, we use monitoring tools, regular testing, and automated reports:

1. Set up monitoring in Google Search Console. Regularly check the status of “good”, “bad”, and “need improvement” pages. Data can be entered into Google Sheets.
2. Regular testing with PageSpeed Insights
3. Start optimizing with the pages that bring the most traffic. Optimize the mobile version. Testing should be done first after each change, and then possibly once a week, and then once a month.

Conclusions

Google Core Web Vitals are important metrics that determine how fast and user-friendly a website is. They measure how long it takes to load the main content (LCP), how quickly the site responds to user actions (FID), and whether the content is shifted during loading (CLS). Optimizing these metrics helps to make your website more comfortable for visitors, reduce bounce rates, and improve your position in Google search results.

To ensure that your website remains fast and user-friendly, it is important to regularly check its Core Web Vitals metrics. To do this, use Google Search Console, PageSpeed Insights, and Lighthouse. And in order not to miss any problems, you can set up automated reports to help you track changes and respond quickly to possible difficulties.

Improvements to Core Web Vitals not only raise your site in Google search, but also make it more user-friendly. Fast loading, smooth operation, and a stable interface help retain visitors, increase conversions, and build trust in the site. Investing in these indicators is an investment in the sustainable growth and success of your project.

Regularly analyze and improve Core Web Vitals to make your site more user-friendly and gain an edge over your competitors in Google search!