Decoding Google’s Core Web Vitals: What Every Website Owner Should Know

January 17, 2024
Will Kramer
Decoding Google's Core Web Vitals: What Every Website Owner Should Know

Every great app has a great website to support it – to tell your company’s story, to drive downloads, sometimes to provide user support. Having a website that looks good on any device is just the tip of the iceberg when it comes to delivering a great online experience. Underneath the surface lies a world of metrics and measurements that can make or break your website’s performance, especially in the eyes of search engines like Google. When Rocket Farm Studios conducts an audit of existing websites, we don’t just skim the surface for aesthetic appeal; we dive deep into the heart of what makes a website truly perform — its Core Web Vitals.


Defining Core Web Vitals

Google’s Core Web Vitals are a set of essential performance metrics that gauge the user experience of a website. Comprising three key factors—Largest Contentful Paint (LCP), First Input Delay (FID), and Cumulative Layout Shift (CLS)—Core Web Vitals measure loading speed, interactivity, and visual stability. Core Web Vitals are a set of specific performance metrics that Google has determined to be crucial to a webpage’s overall user experience. They’re not just arbitrary numbers; they are the pulse of a website, indicating its health and efficiency in delivering content to the end-user. In essence, these vitals assess how quickly your site loads, how soon it becomes interactive, and how stable it is as it renders on different devices.


Why They Matter

Why do these factors matter? Because they directly affect how users perceive your website. A site that loads quickly and functions smoothly retains users longer and makes them more likely to return. Moreover – and this is critical to understand – Google uses these vitals as ranking signals for search results, meaning they can significantly influence where your site stands in the competitive search landscape.

To help you navigate through the technicalities and importance of Core Web Vitals, Rocket Farm Studios offers a simplified guide. It’s important to note that while these metrics might sound technical, they fundamentally aim to quantify the user experience — something that any website owner should prioritize. After all, what good is a website if it’s not serving its users effectively?

With this mindset, let’s explore Core Web Vitals and break down what each metric means and how it affects your online presence. Whether you’re looking to build a new website or optimize an existing one, understanding these vitals will give you the insight needed to ensure your website not only looks good but performs exceptionally well too.


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1. Largest Contentful Paint (LCP) – Load Time of Main Content

LCP focuses on how quickly the content of a webpage is visibly populated. The content that LCP considers could be an image, a block of text, or a video – essentially, the heaviest content piece that largely defines the user’s experience on that page. You can usually find this content at the very top of a page, or what we call “above the fold” before you start scrolling down. If a website has an LCP greater than 2.5 seconds, it’s considered slow, and the longer a user waits, the more likely they are to leave the site. Therefore, optimizing images, server response times, and rendering patterns is crucial.

Our Tips:

  1. Use Next-Generation Image Formats: Implement image formats like WebP, which offer better compression and quality characteristics compared to traditional formats like JPEG or PNG. This can significantly reduce the load time of images, which are often the largest elements on a page.
  2. Implement Lazy Loading: Lazy loading defers the loading of non-critical resources at page load time. Instead, these resources are loaded at the moment they are needed (like when they enter the viewport). This reduces initial load time and saves bandwidth for users who don’t scroll through the entire page.
  3. Optimize CSS and JavaScript: Review and minimize the size of CSS and JavaScript files. Eliminate unnecessary code, and use minification tools to reduce file size. Consider splitting your CSS and JavaScript into critical and non-critical files, and load only what’s needed for the initial view.
  4. Leverage a Content Delivery Network (CDN): CDNs store copies of your content in multiple geographical locations. This means that when a user requests your website, the content is delivered from the nearest server, reducing the time it takes to load your page.

2. First Input Delay (FID) – Interaction Readiness

This metric measures the time it takes for a page to become interactive. A good FID ensures that when users click a link or a button, the site responds quickly and without delay. This is critical for pages requiring user interaction, such as forms and login pages. To improve FID, minimizing (or deferring) JavaScript execution can be key, ensuring nothing blocks the browser from responding to user inputs as quickly as possible once the page begins loading.

Our Tips:

  1. Minimize or Defer JavaScript: Large JavaScript files can significantly delay the time it takes for a page to become interactive. Minimizing these files and deferring non-essential JavaScript until after the main content has loaded can reduce the load time. You can use techniques like asynchronous or deferred loading to achieve this.
  2. Break Up Long Tasks: Long tasks can block the main thread and delay the time to interaction. Breaking these tasks into smaller, manageable chunks allows the browser to handle user interactions in between these tasks, improving responsiveness.
  3. Remove Non-Essential Third-Party Scripts: Third-party scripts, like trackers or ads, can also impact your site’s interactivity. Evaluate and remove any non-critical third-party scripts, or defer their loading to a later point in time.
  4. Leverage Browser Caching: Utilizing browser cache effectively means that repeat visitors to your site will experience faster load times. When resources like stylesheets, images, and JavaScript files are cached by the browser, it eliminates the need to reload them on subsequent visits, enhancing the overall user experience.


3. Cumulative Layout Shift (CLS) – Visual Stability

A stable page means less annoyance for users. High CLS scores indicate that elements on the page are shifting while the user is trying to interact with it. If your site’s content jumps around as the page loads, likely poor CLS is to blame. This can happen when images load without dimensions, fonts render differently than expected, or dynamic content populates late. To reduce CLS, specify size attributes for images and video elements, and reserve space for ad elements before they load.

Our Tips

  1. Include Width and Height Attributes in Image and Video Elements: By specifying the width and height attributes in the HTML for images and videos, you are effectively reserving space for these elements in the web page layout. This means that when the page is initially rendered in the browser, it allocates space for these elements even before they have fully loaded. As a result, once the images or videos do load, they fit into the allocated space without causing the layout to change. This practice is crucial for improving the Cumulative Layout Shift (CLS) score, a key metric in Google’s Core Web Vitals.
  2. Managing Dynamically Injected Content: When content (like ads, widgets, or images) is dynamically added to a page, it can cause the content that the user is currently viewing to move, creating a poor user experience. To prevent this, any dynamically injected content should be added in a manner that doesn’t disrupt the existing layout. Ideally, this means:
    1. Adding new content below the current viewport, so the user doesn’t see the layout shift as they are reading or interacting with the page.
    2. If the content must be added within the current viewport, it should be done in a way that does not push existing content around. For example, by using placeholders or reserving space in advance, similar to setting width and height for images.
  3. Impact on User Experience and SEO: Sudden layout shifts can be disorienting and frustrating for users, especially if they are trying to click a link or button and the layout suddenly changes, causing them to click on something else. Furthermore, since Google considers CLS as a part of its ranking factors for search engine optimization (SEO), poorly managed layout shifts can negatively impact a website’s search engine rankings.
  4. Tools and Techniques for Improvement: Web developers can use various tools to measure and improve CLS. Google’s Lighthouse, for example, is a popular tool for auditing this aspect of web performance. Additionally, employing responsive design techniques, utilizing CSS Grid and Flexbox for layout management, and testing the site on various devices and connection speeds can help in identifying and fixing layout shift issues.


4. Real User Monitoring – User-Centric Data

Real User Monitoring (RUM) allows you to see how your website performs in the hands of actual users. This means the metrics reflect a variety of real-world conditions and user interactions. By focusing on how your site performs in different situations, you can identify and fix issues that affect users in specific scenarios, like slow mobile networks or devices with low processing power.

Our Tips:

  1. Real User Monitoring (RUM): RUM involves collecting and analyzing data from actual users as they interact with your website. Unlike synthetic monitoring, which simulates user interactions from predefined locations and devices, RUM provides insights based on real-world usage patterns, device types, network conditions, and geographic locations. This data is invaluable in understanding how users actually experience your website.
  2. Using Web Performance Monitoring Tools for Core Web Vitals: These tools can be integrated into your website and will collect data on these vitals as users interact with the site. Examples of such tools include Google’s PageSpeed Insights, Lighthouse, and Chrome User Experience Report.
  3. Understanding Performance Bottlenecks: By analyzing the collected RUM data, you can identify specific performance issues that real users are encountering. For instance, you might discover that users on mobile devices experience longer load times, or users in certain geographical locations face significant layout shifts. This data helps in pinpointing the exact areas where the user experience is being compromised.
  4. Continuous Monitoring and Improvement: RUM is not a one-time task but an ongoing process. User behavior and web technologies are constantly evolving, so continuous monitoring is essential. Regular analysis of RUM data helps in keeping track of how changes to your website affect user experience and allows for timely adjustments.


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5. Consistency Across Page Types – Unified Performance

By grouping similar pages, you can understand which templates or types of content are performing well and which aren’t. This helps you streamline your optimization efforts and focus on high-impact areas. For example, if your product pages are slow, improving their load time could directly increase sales.

Our Tips

  1. Group Pages by Template for Analysis: Different page types (like product pages, blog articles) often follow specific templates. Analyze performance data for each template to understand which ones are underperforming.
  2. Prioritize Optimization for Worst-Performing Templates: Identify the page template with the poorest performance metrics. Focusing your optimization efforts on these areas can have the most significant impact.
  3. Implement A/B Testing: Use A/B testing to assess the effectiveness of your optimizations. This involves comparing a version of the page with optimizations against a control version without changes, allowing you to measure the impact on performance.
  4. Balance Performance, Functionality, and Design: Ensure that optimizations improve performance without compromising the page’s functionality or design. A/B testing can help confirm that enhancements don’t negatively affect user experience.


6. Data Reliability – Trustworthy Insights

Google’s thresholds for Core Web Vitals ensure that the data you’re looking at is based on a robust set of user interactions. This reliability helps you make informed decisions about where to invest your time and resources in improving your site.

Our Tip:

  1. Data Reliability for Trustworthy Insights: Google sets thresholds for Core Web Vitals based on extensive user interaction data. This ensures that the data you analyze is robust and reliable, guiding you in prioritizing optimization efforts effectively.
  2. Regular Performance Audits with Tools: Use tools like Google’s PageSpeed Insights and to conduct regular performance audits of your site. has developed a page speed checker that allows you to test hundreds of URLs automatically. All you have to do is enter a URL, and the tool crawls the website and determines the page speed scores for each subpage. These tools provide valuable insights into various performance metrics.
  3. Compare Lab and Field Data: It’s crucial to compare lab data (which is based on simulated performance testing) with field data (which represents real-user performance). This comparison helps verify that your testing environment mirrors the actual user experience.
  4. Accurate Reflection of User Experience: Ensuring your testing environment accurately reflects real user experience is key. It helps identify genuine performance issues and opportunities for improvement that will impact users directly.


7. Keeping Up with Web Evolution – Future-Proofing

As the internet and user habits change, so do the Core Web Vitals. Staying updated with Google’s evolving standards can help you future-proof your website and maintain a competitive edge in search rankings.

Our Tips:

  1. Adapt to Changes in Internet and User Habits: The internet and user habits are constantly evolving, which means Core Web Vitals and other performance standards do too. Staying updated with these changes is crucial for keeping your website relevant and efficient.
  2. Future-Proof Your Website: By keeping up with the latest trends and standards, you can future-proof your website. This helps maintain its competitive edge, particularly in search rankings where performance and user experience are key factors.
  3. Stay Informed Through Reliable Sources: Subscribe to Google’s webmaster blog and engage with web development communities. These platforms provide timely updates on changes in web standards and Core Web Vitals.
  4. Proactive Site Adjustments: Staying informed enables you to proactively make adjustments to your site. This readiness ensures your website consistently aligns with the latest best practices in web development and performance optimization.


8. Looking at the Big Picture – Overall Health Check

Sometimes, there isn’t enough page-level data to assess performance reliably. In these cases, Google uses broader data to give an overall health check of your site, ensuring even small and new sites get accurate performance readings.

Our Tips:

  1. Broad Overview for Overall Health: For small or new sites with limited page-level data, it’s essential to look at broader website performance metrics. This holistic view helps in understanding the site’s overall health and identifying areas for improvement.
  2. Using Google Search Console: Google Search Console is a valuable tool for this purpose. To access it, simply log in to your Google account and navigate to the Search Console (you can find it by searching for “Google Search Console” in your web browser). Once there, you need to verify your site ownership by following Google’s instructions.
  3. Performance Analysis in Google Search Console: In the Search Console, you’ll find various reports that provide insights into your site’s performance. These include data on search traffic, mobile usability, and site errors. While it doesn’t specifically mention Core Web Vitals, these reports collectively give a comprehensive overview of your site’s health.
  4. Identifying Widespread Issues: Look for common patterns or recurring issues in these reports. This might include mobile usability problems, crawl errors, or pages with low search traffic. Understanding these issues is crucial for prioritizing improvements.
  5. Making Data-Driven Decisions: Use the insights from Google Search Console to make informed decisions about where to focus your optimization efforts. For example, if there’s a recurring mobile usability issue, prioritizing mobile optimization would be beneficial.


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9. Global User Experience – Worldwide Standards

The Core Web Vitals are designed to reflect a global standard for user experience, taking into account the diversity of web users. This means your site’s performance is assessed against the expectations of users around the world, not just in a single region.

Our Tips:

  1. Core Web Vitals as Global Standards: The Core Web Vitals are established to provide a universal benchmark for user experience, catering to the varied expectations of users worldwide. Your site’s performance is measured against these global standards, not just based on users in a single region.
  2. Conduct User Testing Globally: To understand how your website performs across different geographical locations, conduct user testing with participants from various regions. This can be done through online platforms that allow you to reach a global audience. Ensure that you’re testing on a range of devices to account for different usage patterns and technology access.
  3. Optimize Content Delivery Internationally: Use international Content Delivery Networks (CDNs) to speed up the loading time of your website for users around the world. CDNs store copies of your site’s content on servers located in various geographical locations, reducing the distance data needs to travel.
  4. Localize Resources for Different Regions: Besides using CDNs, localize resources like images, videos, and text to cater to different regional audiences. This might involve translating content into different languages, using region-specific images, and ensuring that cultural nuances are respected.
  5. Monitor Performance Across Regions: Regularly check your website’s performance in different regions. Tools like Google Analytics can provide insights into how your website is performing globally. Pay attention to metrics like load time, bounce rate, and user engagement in different countries.


10. Guidance and Tools for Improvement – Actionable Solutions

Google’s tools like PageSpeed Insights and Lighthouse don’t just point out problems; they provide clear guidance on how to fix them. These recommendations are actionable and often come with detailed explanations, so you can understand the reasoning behind each suggestion and prioritize changes that will have the most significant impact.

Our Tips:

  1. Actionable Guidance from Google Tools: Tools like PageSpeed Insights and Lighthouse are designed to do more than just identify problems; they offer clear, actionable advice on how to resolve these issues. These recommendations typically come with detailed explanations, helping you understand why each change is beneficial and how it impacts your site’s performance.
  2. Focus on Diagnostics and Opportunities in Lighthouse: When using Lighthouse, pay special attention to the ‘Diagnostics’ and ‘Opportunities’ sections. These areas provide targeted advice for improving each Core Web Vital. They break down specific problems and suggest optimizations that can significantly enhance site performance.
  3. Testing Changes in a Staging Environment: Before applying changes directly to your live site, implement them in a staging environment. This approach allows you to test the modifications without affecting your real users. A staging environment is essentially a clone of your live site where you can safely experiment and validate the impact of changes.
  4. Measuring Impact Pre-Launch: After implementing the recommended changes in the staging environment, measure their impact on site performance. Use the same tools (like Lighthouse) to assess the improvements. This step is crucial to ensure that the changes have the desired effect and don’t introduce new issues.
  5. Deploying Optimizations to Live Site: Once you’re confident that the changes are beneficial, roll them out to your live site. Continue to monitor the site’s performance after these changes to ensure they’re delivering the expected results and positively influencing your Core Web Vitals.


Final Thoughts

Google’s Core Web Vitals might seem intimidating at first glance, with their technical requirements and impact on search rankings. However, rather than something to fear, these vitals should be viewed as a valuable guide—one that leads developers and marketers towards creating websites that offer superior experiences to their users.

Understanding and respecting the Core Web Vitals is essential because, at their heart, they are about the user’s experience. They remind us that a website is more than just a digital brochure; it is a dynamic platform for interaction, information, and engagement. These metrics push us to build not just beautiful websites but also responsive, stable, and efficient ones that users can rely on and enjoy.

Moreover, the implementation of Core Web Vitals is not just about appeasing algorithms or boosting SEO; it’s about commitment to your audience. Ensuring your website is performing and user-friendly can lead to increased engagement, lower bounce rates, and ultimately, higher conversion rates. It’s about building trust with your visitors, showing them that you value their time and experience.

Whether you are a developer looking to refine your website or a marketer striving to enhance user engagement, embracing Core Web Vitals with the help of Rocket Farm Studios can pave the path to a successful and future-proof website. 

Let these metrics be your compass, pointing you towards a user-centric approach that not only aligns with Google’s vision but also aligns with providing exceptional digital experiences for your audience.

Our Final Tip: 

Consider NitroPack for Efficient Website Optimization – In our experience with various clients, NitroPack has been a helpful tool in improving website performance. It offers automated features like caching, image compression, and code minification, potentially reducing manual development work. While it’s effective for many, we recommend evaluating its impact in your specific context to ensure it aligns with your site’s optimization needs and goals.

So, if you don’t know where to get started with a blueprint for your app, Rocket Farm Studios can take the pressure off.

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I hope you enjoy reading this blog post.

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