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Core Web Vitals Optimization guide

Core Web Vitals Optimization Guide for Beginners in 2023 | Stand Out Now

In the vast online world, ensuring your website stands out is crucial. Core Web Vitals, the heartbeat of user experience and SEO are the metrics that determine your site’s performance. In this core web vitals optimization guide, we’ll walk you through the essentials in the simplest way possible.

I’ve explained all in sections for your ease.

Let’s quickly jump into it!

Section 1


Understanding Core Web Vitals | A Must-Have Target

Core Web Vitals Optimization

Getting to Know Core Web Vitals

At its core, Core Web Vitals consists of three metrics:

  1. Largest Contentful Paint (LCP)
  2. First Input Delay (FID)
  3. Cumulative Layout Shift (CLS)

Think of LCP as the time it takes for your website to load its main content, FID as its responsiveness, and CLS as its stability.

Why Do They Matter?

Imagine a visitor entering your site. They expect seamless navigation. If your website takes forever to load (high LCP), responds slowly (high FID), or shifts unexpectedly (high CLS), you risk losing them to a competitor. Plus, Google loves speedy, user-friendly websites, and they reward them with higher rankings.

Google Page Speed Test| Your Website Loading Speed & Bounce Rate

Google Page Speed Test for Desktop

Google Page Speed Test is a tool that checks how fast your website loads. It’s crucial because fast-loading sites make visitors happy. To keep the score high for both mobile and desktop, optimize images, use clean code, and minimize server requests.

Since more people use mobiles, prioritize mobile optimization to ensure a smooth experience for the majority of your visitors.

Google Page Speed Test for Mobile

The Page Speed Test is highly effective in measuring your website’s loading speed. Expert SEOs emphasize running the test properly, which means following the tool’s guidelines precisely. It helps identify areas needing improvement, ensuring your website loads quickly and provides a seamless experience.

Proper testing ensures accurate results, enabling you to optimize your site effectively for better user satisfaction and improved search engine rankings.

How Does Website Speed Affect Bounce Rate?

Website speed significantly impacts bounce rate. When a website loads slowly, visitors tend to get frustrated and may leave before the page fully loads. A high bounce rate occurs when visitors leave your site quickly after viewing only one page, indicating dissatisfaction.

Faster-loading websites create a better user experience, reducing bounce rates. Users are more likely to engage, explore multiple pages, and stay longer on a site that loads quickly, improving overall user satisfaction and website performance.

Webpage Test | A Comprehensive Tool


Webpage Test | A Comprehensive Tool

to check your Cor Web Vitals analysis, just go to the Web Page Test website for the following matrics.

Page Performance Metrics

  1. Time to First Byte
  2. Start Render
  3. First Contentful Paint
  4. Speed Index
  5. Largest Contentful Paint
  6. Cumulative Layout Shift
  7. Total Blocking Time
  8. Page Weight

1. Time to First Byte (TTFB)

It is a web performance metric that measures the time taken by a web server to respond to a request from a browser. It represents the time interval between the browser making an HTTP request to the server and receiving the first byte of the response containing the web page’s content.

TTFB is crucial because it indicates how quickly a web server processes and delivers the initial data to the user’s browser. A fast TTFB contributes to a quicker loading time for the entire web page. Several factors, including server processing time, network latency, and server configuration, can influence TTFB.

Ideal Time to First Byte

An ideal TTFB is typically under 200 milliseconds (ms). However, the exact ideal TTFB can vary based on the complexity of the website, the server’s location, and the user’s geographical location.

The faster the TTFB, the better, as it ensures a more responsive user experience. Websites with a slow TTFB might benefit from server optimizations, content caching, or using Content Delivery Networks (CDNs) to reduce latency and improve the server’s response time.

How to optimize Time to First Byte (TTFB)?

Optimizing Time to First Byte (TTFB) is crucial for improving your website’s server response time and ensuring a faster loading experience for users. TTFB measures the time it takes for the server to respond to a request from the browser. Here are several strategies to optimize TTFB:

Choose a Fast Web Hosting Provider

  • Server Location: Choose a server location that is geographically close to your target audience. Hosting your website on servers located near your users reduces network latency.
  • Quality Hosting: Invest in high-quality hosting services that offer optimized server configurations, hardware, and network infrastructure.

Utilize Content Delivery Networks (CDNs)

  • CDN Services: Use CDNs to cache and distribute your website’s content across multiple servers worldwide. CDNs deliver content to users from servers located closer to their geographical location, reducing latency and improving TTFB.
  • Static Content: Offload static resources like images, CSS, and JavaScript files to the CDN. Dynamic content can also benefit from caching mechanisms provided by CDNs.

Optimize Server Configuration

  • Enable Compression: Enable Gzip or Brotli compression on your server to compress responses before sending them to the browser. Compressed files reduce response size and speed up data transmission.
  • Browser Caching: Set appropriate caching headers to allow browsers to cache static resources locally. Proper caching reduces the need for repeated requests to the server, improving TTFB for subsequent visits.

Database Optimization

  • Query Optimization: Optimize database queries to reduce the time it takes to fetch data. Use indexed fields and avoid unnecessary complex queries.
  • Database Caching: Implement caching mechanisms at the database level. Use object caching and query caching to store query results and database objects, reducing the need for repeated database calls.

Implement Efficient Server-Side Scripting

  • Server-Side Language: Choose an efficient server-side language and framework. Some languages and frameworks are inherently faster and more optimized than others.
  • Optimize Code: Optimize server-side code for better performance. Minimize the use of unnecessary functions and loops. Profile your code to identify bottlenecks and optimize accordingly.

Utilize Web Server Optimizations

  • Web Server Software: Choose a fast and efficient web server software such as Nginx or LiteSpeed. Configure the server for optimal performance and tweak settings like the maximum number of connections and worker processes.
  • HTTP/2: Enable HTTP/2, which allows multiple requests and responses to be multiplexed over a single connection, reducing latency and improving overall performance.

Monitor and Diagnose Performance Issues

  • Monitoring Tools: Use server monitoring tools to identify performance bottlenecks and server resource usage. Regularly monitor server logs, CPU usage, memory usage, and disk I/O to diagnose potential issues.
  • Error Handling: Implement proper error handling and logging to identify and address issues promptly. Monitor 5xx server errors and investigate their causes.

Regularly Update Software and Plugins

  • Software Updates: Keep your web server software, content management system, plugins, and libraries up-to-date. Updates often include performance improvements and security fixes.

Here is our net point to discuss.

2. Start Render

It is another important web performance metric that measures the time it takes for the first visual elements of a web page to appear on the user’s screen. It marks the moment when the browser begins to render content and the user starts seeing a visual representation of the web page.

Unlike Time to First Byte (TTFB), which focuses on server response time, Start Render considers the entire process of loading and rendering the web page, including downloading resources like HTML, CSS, JavaScript, and images, and processing them to display the initial visible content.

Ideal Start Render Time

The ideal Start Render time is generally considered to be under 1 to 2 seconds. This means users should see meaningful content and visual elements on the screen within this timeframe, providing them with a sense of progress and interactivity while the rest of the page continues to load.

Achieving a fast Start Render time involves optimizing various aspects of web design and development, including efficient coding practices, minimizing the use of render-blocking resources, optimizing images, and prioritizing critical content to load first.

Additionally, techniques like asynchronous loading of non-essential scripts and stylesheets can help improve Start Render times, ensuring a smoother and more engaging user experience.

How to optimize Start Render?

Optimizing Start Render is crucial for delivering a fast and engaging user experience. Start Render represents the moment when the first visual elements of a web page begin to appear on the screen. Here are several strategies to optimize Start Render:

Minimize Render-Blocking Resources

  1. CSS: Minimize the use of render-blocking CSS. Inline critical styles or use the preload attribute for critical stylesheets to ensure they load early.
  2. JavaScript: Defer non-essential JavaScript. Load scripts asynchronously or use the async attribute to prevent them from blocking the rendering process.

Optimize Critical Resources

  • Critical Path CSS: Identify and load critical CSS inline to style above-the-fold content immediately.
  • Lazy Loading: Lazy load non-critical images and videos. Use the loading="lazy" attribute for images and the loading="lazy" parameter for videos to defer their loading until they come into the viewport.

Prioritize Above-the-Fold Content

  • HTML Structure: Ensure that the HTML structure of above-the-fold content loads first. Organize your HTML so that essential content appears early in the document.
  • Images: Optimize and prioritize above-the-fold images. Compress images and use modern formats like WebP. Load crucial images using the preload or async attributes.

Minimize Server Response Time

  • Server Optimization: Optimize your server configuration and leverage caching mechanisms. Use Content Delivery Networks (CDNs) to distribute content closer to users, reducing server response time.

Efficiently Load External Resources

  • Third-Party Scripts: Be cautious with third-party scripts. Load them asynchronously or defer their execution. Third-party scripts can significantly impact Start Render time.
  • Fonts: Optimize web fonts. Use font-display: swap; in your CSS to ensure text remains visible while web fonts load. Limit the number of font styles and weights used on your website.

Use Resource Hints

  • Preconnect: Use <link rel="preconnect"> to establish early connections to domains serving essential resources.
  • DNS Prefetch: Use <link rel="dns-prefetch"> for domains hosting resources required for rendering above-the-fold content.

Optimize CSS and JavaScript

  • CSS: Minimize CSS files and optimize selectors. Remove unused styles. Consider using CSS methodologies like BEM (Block Element Modifier) to write efficient and maintainable stylesheets.
  • JavaScript: Optimize and compress JavaScript. Remove unnecessary functions and libraries. Consider code splitting to load only necessary JavaScript for the initial view.

Regularly Monitor and Audit

  • Performance Tools: Use tools like Google PageSpeed Insights, Lighthouse, and WebPageTest to monitor your website’s performance regularly. Identify bottlenecks and areas for improvement.
  • Audits and Profiling: Use browser developer tools to conduct audits and performance profiling. Identify performance issues, optimize critical paths, and address bottlenecks.

Now let’s move on.

3. First Contentful Paint (FCP)

It is a key performance metric that measures the time it takes for the first piece of content to appear on the screen when a user visits a web page. This content can be anything visible, such as text, images, or background colors. FCP provides insights into the initial loading experience and indicates when users perceive that the web page is starting to display useful content.

Unlike Start Render, which focuses on the rendering of visual elements, FCP specifically tracks the rendering of the first content element, giving a more precise measure of when users begin to see meaningful information on the page.

Ideal First Contentful Paint Time

An ideal FCP time is typically under 1 to 2 seconds. Achieving a fast FCP time is crucial because it ensures that users perceive the web page as responsive and engaging, even during the initial loading phase. A quick FCP time contributes to a positive user experience, reducing bounce rates, and improving overall user satisfaction.

How to optimize First Contentful Paint Time?

To optimize First Contentful Paint time, web developers should focus on techniques such as:

  • Optimizing Critical Resources: Prioritize loading essential resources, such as fonts and CSS, to ensure that the first content element is displayed quickly.
  • Minimizing Render-Blocking Resources: Identify and defer or async render-blocking scripts and stylesheets to prevent delays in rendering content.
  • Image Optimization: Compress and resize images appropriately to reduce their file size, enabling faster loading without compromising quality.
  • Server Configuration: Optimize server settings and leverage caching mechanisms to reduce the time it takes to fetch resources.
  • Code Splitting: Implement code splitting techniques to load only necessary JavaScript for the initial view, deferring the rest until it’s required for user interaction.

4. Speed Index

It is a web performance metric that measures how quickly the content of a web page is visually displayed during the loading process. Unlike metrics which focus on specific elements, Speed Index provides a holistic view of the entire loading experience. It considers the visual completeness of the page at various points in time.

Speed Index is calculated by evaluating how much of the visible area of the browser viewport is covered by rendered content during the loading process.

A lower Speed Index value indicates a faster-loading page, where users perceive the content appearing more quickly on the screen.

Ideal Speed Index

An ideal Speed Index time depends on the complexity of the web page, but generally, lower values are better. Websites should aim for a Speed Index below 1,000 to provide a fast and visually complete loading experience.

How to optimize the Ideal Speed Index?

To optimize Speed Index, web developers can focus on several strategies:

  • Minimize Render-Blocking Resources: Identify and defer or asynchronously load scripts and stylesheets that block the rendering process. This allows critical content to be displayed more quickly.
  • Optimize Images and Multimedia: Compress images and videos, and consider using modern image formats like WebP to reduce file sizes without compromising quality. Lazy loading techniques can also be applied to multimedia elements.
  • Prioritize Above-the-Fold Content: Load and render essential content above the fold first, allowing users to start interacting with the page while additional resources load in the background.
  • Implement Critical CSS: Deliver essential styles inline or through asynchronous loading to ensure that the initial visible content is styled promptly.
  • Reduce Server Response Time: Optimize server configurations, use Content Delivery Networks (CDNs), and employ efficient server-side caching to reduce the time it takes to fetch resources.

5. Largest Contentful Paint (LCP)

It is a core web vital that measures the loading performance of a web page. It specifically focuses on the loading time of the largest content element visible within the user’s viewport. This content element can be an image, video, or a large block of text, essentially any significant piece of content that appears on the screen without scrolling.

LCP is a critical metric because it directly correlates with the user’s perception of a web page’s loading speed. When the largest content element loads quickly, users feel that the page is loading fast, leading to a better user experience.

Ideal Largest Contentful Paint Time

An ideal LCP time is typically under 2.5 seconds. Achieving an LCP within this timeframe ensures that users perceive the loading process as seamless and the web page as responsive.

How to optimize the Largest Contentful Paint Time?

To optimize Largest Contentful Paint, consider the following strategies:

  • Optimize Images and Videos: Compress and resize images and videos to reduce their file sizes. Use modern image formats like WebP and efficient video codecs to deliver high-quality visuals with smaller file sizes.
  • Lazy Loading: Implement lazy loading for images and videos. Lazy loading delays the loading of non-essential media elements until they are about to come into the user’s viewport, improving initial loading times.
  • Prioritize Critical Resources: Identify the largest content element and ensure that the resources needed to render it, such as images or stylesheets, are prioritized. Load critical resources as early as possible in the page’s loading process.
  • Efficient Server-Side Rendering: Optimize server response times and consider server-side rendering techniques to generate and deliver HTML content more efficiently.
  • Use Content Delivery Networks (CDNs): Distribute your content across servers located in various geographical locations using CDNs. CDNs cache content closer to users, reducing the time it takes to fetch resources.

6. Cumulative Layout Shift (CLS)

It is a core web vital that measures the visual stability of a web page. It quantifies the unexpected layout shifts that occur during the loading process. These shifts can happen when elements on the page, such as images or ads, load asynchronously, causing the content below them to move suddenly. CLS helps in evaluating how often and how significantly these layout shifts affect the user experience.

Ideal Cumulative Layout Shift Score

An ideal CLS score is typically less than 0.1. A CLS score below this threshold indicates a stable and visually seamless browsing experience for users.

How to Optimize Cumulative Layout Shift?

To optimize Cumulative Layout Shift and create a more stable user experience, consider the following strategies:

  • Set Explicit Dimensions for Media: Always include width and height attributes for images, videos, and other media elements. This ensures that the browser knows the dimensions in advance, preventing unexpected shifts when the content loads.
  • Preload Important Resources: Use the rel="preload" attribute for critical resources such as fonts and stylesheets. Preloading these resources informs the browser that these assets are essential, allowing them to load earlier in the rendering process and reducing layout shifts.
  • Avoid Dynamically Injected Content: Be cautious when injecting content dynamically into the page, especially above existing content. If dynamic content is necessary, reserve space for it in the layout to prevent sudden shifts when the content appears.
  • Implement Responsive Design Practices: Use responsive design techniques to ensure that the layout adapts gracefully to different screen sizes and devices. Avoid fixed-size elements that might not fit well on various devices, causing layout shifts.
  • Regularly Test and Debug: Continuously monitor your website’s layout stability using tools like Google PageSpeed Insights or Lighthouse. Identify and fix any layout shift issues that arise during the testing process.

7. Total Blocking Time (TBT)

Yes, itis a crucial web performance metric that measures the total duration during which a web page is unresponsive to user input because the main thread is busy with tasks such as loading and executing JavaScript code. In simpler terms, TBT quantifies the period during which users experience delays in interacting with a web page due to script execution.

Ideal Total Blocking Time

An ideal TBT is typically less than 300 milliseconds. Keeping TBT below this threshold ensures that users can interact with the web page promptly, providing a smooth and responsive user experience.

How to Optimize the Total Blocking Time?

To optimize Total Blocking Time and enhance the interactivity of your web pages, consider the following strategies:

  • Minimize and Optimize JavaScript: Reduce the amount of JavaScript code loaded on your web page. Optimize and refactor JavaScript functions to be more efficient, and eliminate unnecessary scripts. Consider code-splitting techniques to load only essential scripts initially.

protip_iconPro Tip

Use tools like tree shaking and minification to eliminate unused code and reduce the size of JavaScript files.

  • Defer Non-Essential JavaScript: Defer the loading and execution of non-essential JavaScript until after the initial page load. This ensures that critical interactive elements are not delayed by script execution.

protip_iconPro Tip 

Utilize the defer attribute in script tags to defer non-essential scripts while ensuring they are executed in order after the document has been parsed.

  • Optimize Third-Party Scripts: Evaluate and optimize third-party scripts and services that your web page relies on. Consider asynchronous loading for third-party scripts to prevent them from blocking the main thread.

    protip_iconPro Tip

Use Content Security Policy (CSP) to control and mitigate the impact of third-party scripts on your web page’s performance and security.

  • Implement Efficient CSS: Optimize CSS styles to avoid render-blocking and minimize layout recalculations. Use CSS media queries and avoid unnecessary style recalculations for off-screen elements.

protip_iconPro Tip

Leverage CSS Grid and Flexbox for efficient and responsive layouts, reducing the need for complex and time-consuming CSS computations.

  • Use Web Workers: Offload time-consuming tasks to web workers, which run in the background without blocking the main thread. Web workers enable parallel processing, allowing your web page to remain responsive to user interactions.

protip_iconPro Tip

Consider implementing web workers for tasks like data processing, image manipulation, and other CPU-intensive operations.


8. Page Weight

It refers to the total size of a web page, including all its resources such as HTML, CSS, JavaScript files, images, videos, and other multimedia elements. It is measured in bytes or kilobytes (KB) and directly affects the loading speed and performance of a website. A lighter page with fewer resources generally loads faster and provides a better user experience.

Ideal Page Weight

An ideal page weight depends on the type of website and the expectations of the target audience. However, as a general rule, web developers aim to keep the total page weight as low as possible, ideally below 500 KB for basic content websites and under 1-2 MB for more complex websites with multimedia elements.

To optimize Page Weight and ensure faster loading times, consider the following strategies:

  • Compress and Optimize Images: Use image optimization techniques to reduce the file size of images without compromising quality. Choose appropriate image formats (such as WebP) and employ tools to compress images effectively.

    protip_iconPro Tip

Utilize responsive images and the srcset attribute to serve different image sizes based on the user’s device and screen resolution.

  • Minimize and Concatenate CSS and JavaScript Files: Reduce the number of CSS and JavaScript files by combining them into larger, minified files. Minification removes unnecessary spaces, comments, and characters, reducing file sizes.

    protip_iconPro Tip

Implement lazy loading for non-essential JavaScript files to defer their loading until they are required, improving initial page load times.

  • Use Efficient Code and Frameworks: Write clean, efficient, and optimized code. Avoid unnecessary libraries or frameworks that add extra weight to the page. Choose lightweight libraries and tools where applicable.

    protip_iconPro Tip

Regularly update and audit third-party libraries to ensure you are using the latest, optimized versions.

  • Optimize Fonts: Limit the number of different fonts and font weights/styles used on your website. Use font subsets to include only the characters necessary for your content, reducing the font file size.

    protip_iconPro Tip

Consider using system fonts for a faster initial rendering of text while web fonts are loading.

  • Minimize Use of Plugins and Widgets: Limit the use of plugins, widgets, and external embedded content, as they often come with additional scripts and stylesheets that contribute to page weight.

    protip_iconPro Tip

Regularly review and remove outdated or unused plugins and widgets to keep the website lean.


Section 2

Optimizing Largest Contentful Paint (LCP) | First Mark

Core Web Vitals Optimization

 Streamlining Your Content

Optimize your images, videos, and text. Compress large images and use formats like JPEG 2000 or WebP for faster loading. For example, instead of using a high-resolution image, resize it to fit your content without compromising quality.

protip_iconPro Tip 

Use online tools like TinyPNG to compress images without losing quality.

Embracing Lazy Loading

Lazy loading ensures that only the visible content loads first, enhancing user experience and reducing LCP. Modern browsers and content management systems (like WordPress) support lazy loading by default.

protip_iconPro Tip 

If you’re using WordPress, simply install a lazy loading plugin to automate the process.

Section 3

Enhancing First Input Delay (FID) | 2nd Mark

Core Web Vitals Optimization 2

Trimming Down JavaScript

Excessive JavaScript execution can slow down FID. Identify unnecessary scripts and either remove them or defer their loading. Prioritize essential scripts to load first.

protip_iconPro Tip

Utilize JavaScript minification tools like UglifyJS to compress your scripts and reduce their size.

Optimizing Server Response Time

A slow server response time can be a culprit for high FID. Upgrade your hosting plan or consider switching to a faster server to improve response time.

protip_iconPro Tip

Consider using Content Delivery Networks (CDNs) to cache your website’s content and serve it to users from servers closer to their location.

Section 4

Minimizing Cumulative Layout Shift (CLS) | 3rd Mark

Stabilizing Elements on Your Page

Ensure that all elements on your website have defined dimensions, especially images and videos. This prevents unexpected shifts during loading.

protip_iconPro Tip

Set explicit dimensions for ads and other dynamic content to prevent layout shifts.

Testing and Debugging

Regularly test your website using tools like Google Page Speed Insights. Identify and fix layout shift issues to provide a seamless browsing experience.

protip_iconPro Tip

Leverage browser developer tools to inspect layout shift causes in real time.

Section 5:

Monitoring and Maintenance | Your 4th Mark

Continuous Monitoring for Success

Regularly monitor your Core Web Vitals using Google’s Search Console. Stay updated on your site’s performance and be ready to make necessary adjustments.

protip_iconPro Tip

Set up email notifications in Google Search Console to receive alerts about any sudden drops in your Core Web Vitals scores.

Listening to User Feedback

Pay attention to user feedback. Your visitors are the best source of information about your website’s user experience.

protip_iconPro Tip 8

Integrate feedback forms on your website and encourage visitors to share their experiences.

Other Related Topics of Core Web Vitals Optimization Guide:



The Path to Success

Optimizing Core Web Vitals might seem daunting, but with the right strategies and tools, it’s achievable. All I’ve listed in the Core Web Vitals Optimization Guide. Remember, a fast and user-friendly website not only pleases your visitors but also wins Google’s favor, leading to higher rankings and increased visibility. Start implementing these tips today, and watch your website soar to new heights!

Faisal Kiani

Faisal Kiani

Muhammad Faisal Kiani is an expert SEO Copywriter, Content Analyst, Strategist, and career counselor. He is enriched by the dynamic experience of 26 years in sales & marketing, management, recruiting, content creation, and career counseling. He is currently working as The Director Operations at Benison Marketing (Pvt.) Ltd.— A real estate consulting and property advising company.

Faisal Kiani has a creative, innovative, and unique approach to SEO copywriting with more than a million words floating in the digital ocean. He prepares beginner to advance levels courses of SEO Copywriting through Amazon Affiliate Blogging, landing pages, and Product Descriptions.

You can also get his first international publication, “The Mystery of Life” on Amazon Kindle soon. Some of his quotes are now published on his website faisalkiani.com as a token.

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