You go to check your speed and performance in Google PageSpeed Insights and see…
Core Web Vitals Assessment Failed
But that’s OK, you’re not alone. In fact, about 56% of origins out there fail the Core Web Vitals assessment.
The good news is you already made the first step, and once you read this article, you’ll know how to join the fortunate 44% of site owners with good Google’s Core Web Vitals and even greater user experience.
Core Web Vitals are a set of performance metrics that Google developed to help site owners measure a webpage's overall user experience. Currently, the three most important Core Web Vitals metrics are:
These metrics were established to provide unified guidance for quality signals essential to delivering a great user experience to your site visitors.
With 40% of users leaving a website if it takes longer than three seconds to load, the last thing you want is a slow or glitchy site.
In fact, in a recent webinar co-hosted with Google, NitroPack revealed just how impatient visitors are and what this means for your online business.
After monitoring 245,433 unique site visits across three ecommerce websites, we learned that:
In summary, the success of your online business is dependent on speed and excellent user experience now more than ever. Failing to pass the Core Web Vitals assessment is an essential indicator your website is not engaging and converting visitors as well as it can.
Fixing poor user experience today opens a door to better rankings in Google Search, more happy visitors, and a boost in your bottom line.
When your site fails the Core Web Vitals assessment, it means that one or more of the three metrics (LCP, FID, or CLS) fall outside of the recommended threshold.
That’s right – if you fail even one of the Web Vitals metrics, you will get the same message in red.
Let’s see why.
Google provides Core Web Vitals assessments using:
To measure Core Web Vitals, Google takes into account all real-user experiences recorded for your website. To pass the Web Vitals, at least 75% of users should experience fast page load, great responsiveness, and no layout shifts as benchmarked by LCP, FID, and CLS.
Lab and field data provide different insights and have distinct use cases:
1. Lab Data
2. Field Data
Although looking at lab data might seem the easier way, to truly deliver an excellent user experience, you must primarily focus on field data.
But how do you know where your Core Web Vitals are sourced from?
Google PageSpeed Insights (PSI) is the most popular testing tool that provides both lab and field data about a page's performance.
When you run your report, the first section you see is the Core Web Vitals assessment. It is generated based on field data from CrUX, and it’s where you’ll find real answers to user experience issues.
Next comes the performance score section generated with lab data from Google Lighthouse. It includes results on First Contentful Paint (FCP), LCP, CLS, Total Blocking Time (TBT), and Speed Index (SI) measured in simulated environments.
In conclusion, while lab data is essential for diagnosing issues and ensuring consistency, field data provides a more accurate representation of how real users experience a site.
Optimizing for Core Web Vitals sourced with field data will have the biggest impact on your business metrics and the success of your online business.
Failing Core Web Vitals can happen for a lot of reasons, like slow server response times, issues with JS and CSS, non-optimized images, excessive HTTP requests, unstable layouts, third-party scripts, etc.
Here's a deep dive into common reasons:
When your server takes too long to start sending data to the user's browser, it can negatively impact your Largest Contentful Paint (LCP) score. This can be due to issues with your web host, the server's physical location relative to the user, or even server misconfiguration. Ensuring a robust server infrastructure, considering a Content Delivery Network (CDN), and optimizing server software can alleviate this.
Heavy and non-optimized images (as well as videos and animations) can significantly slow down page load times. Images that aren't in next-gen formats, are too large or aren't compressed can impact LCP. Consider using formats like WebP, compressing images without losing quality, and utilizing lazy loading for images below the fold.
Whenever you start loading a web page, it sends multiple requests for all of its elements to the browser so the rendering process can begin. Every additional HTTP request—for scripts, images, CSS—adds to the time it takes for a page to load. Reducing these requests by combining files, utilizing sprites for icons, and simplifying your design can improve page speed.
With 53% of abandoned mobile site visits due to 3+ seconds load time, mobile optimization is essential. Issues like non-responsive designs and non-optimized assets for mobile can lead to failing Core Web Vitals, especially on slower mobile networks. Not to mention, this might actually cost your mobile users real money and much-needed data resources.
Cumulative Layout Shift (CLS) is affected when layouts are unstable. Elements that shift around on the page as it loads—like ads popping in, dynamically injected content, or even fonts causing shifts—can contribute to a poor CLS score. Ensure elements have set sizes and avoid adding content above existing content unless it's in response to a user interaction.
Embedded widgets, analytics, ads, and other third-party scripts can significantly slow down a page, impacting several Core Web Vitals. Monitor the performance impact of third-party scripts, defer non-critical third-party scripts, and ensure you're only loading essential external resources.
The “Diagnostics” section in your Google PageSpeed Insights (PSI) report also provides useful information about elements that affect each of the three metrics:
Use this section to generate a list of optimizations you should work on next, or simply steal our checklist instead:
On a side note, the sunset of the FID metric is officially confirmed by Google. As of March 2024, the new responsiveness metric Interaction to Next Pain (INP) will replace FID to provide a more comprehensive insight into the interactiveness of your website.
WordPress, as the most popular CMS worldwide, offers flexibility and a wealth of plugins and themes. However, this can sometimes lead to issues, especially when it comes to performance.
Here are some tailored tips for WordPress users to enhance their Core Web Vitals scores:
Not all hosting services are created equal.
Premium-managed WordPress hosting providers, such as Kinsta, WP Engine, and SiteGround, have fine-tuned their servers specifically for WordPress, ensuring faster server response times and robust caching mechanisms. By choosing a quality host, you can drastically reduce server-related delays and improve the LCP metric.
Content Delivery Networks (CDNs) like Cloudflare, Akamai, and KeyCDN can cache your website content across global servers, ensuring that your users fetch data from a server closer to their location. This significantly improves site speed and LCP times.
By following these WordPress-specific recommendations, not only will your Core Web Vitals scores improve, but your website visitors will also enjoy a smoother and faster browsing experience.
Introducing all the necessary Core Web Vitals optimizations is no easy feat.
Luckily, NitroPack is a lightweight performance optimization service with 35+ advanced features working in sync to guarantee you pass the Core Web Vitals assessment consistently.
A leader in Core Web Vitals optimization, NitroPack is trusted by 200,000+ site owners, developers, and agencies for green web vitals and lightning-fast loading times.
Setting up NitroPack takes 3 minutes and doesn’t require any technical knowledge. Once activated, it works on autopilot, applying CWV-focused optimizations, like:
While occasional audits and fixes can address existing issues, they may not prevent future ones. To maintain a high standard for Core Web Vitals consistently, you need to integrate certain practices into your workflow.
As your website grows, new content gets added, plugins are updated, and user interactions evolve. Regular checks will help you identify and rectify performance dips before they become severe.
A performance budget is a set of limits concerning certain metrics that affect site performance, which must not be exceeded. Instituting a web performance budget can be a game-changer, ensuring that site changes do not negatively affect user experience.
Monitor Violations: Tools like SpeedCurve or Lighthouse CI can be used to track any breaches in your performance budget during development.
Maintain, Review, and Adjust: Over time, as web standards, technologies, and user expectations evolve, revisit your performance budget. Maybe the limits need to be tightened, or perhaps, with better compression and caching tools available, they can be relaxed a bit.
While a 100/100 performance score (e.g., on Google PageSpeed Insights) is impressive, it's not a guarantee that you'll pass Core Web Vitals. This is because the performance score is calculated based on lab data and Core Web Vitals – on field data, i.e. real user interactions. Thus, your site might be fast and responsive in a simulated environment and not perform well in real scenarios, like mobile users visiting your site on a 3G network.
We advise you to shift your focus to optimizing your Core Web Vitals instead of your performance score.
RUM stands for Real User Monitoring. It's a type of data collection method that captures how real-world users are experiencing a website. Unlike synthetic testing, which simulates user interactions in controlled environments, RUM collects data from actual user sessions. This makes RUM invaluable for understanding the true user experience.
When it comes to Core Web Vitals, Google uses RUM data (collected from the Chrome User Experience Report) to determine how users are experiencing a website in the real world. If you're aiming to pass Core Web Vitals, focusing on improving metrics based on RUM data is crucial since this reflects the genuine user experience.
In Google's Page Experience Report, "good" URLs refer to web pages that meet the recommended thresholds for all three Core Web Vitals metrics (LCP, FID, and CLS).
A "good" URL should have:
The "no data" status can arise for various reasons, including:
Lora has 7+ years of experience developing in-depth, specialized content for SaaS companies in the CEE region. She has sourced and collaborated with subject-matter experts on site speed optimization for WordPress, Core Web Vitals, and the future of web performance. "If you can't explain it to a 7-year-old, you've not researched it well enough" is Lora's guiding principle when publishing professional insight for complex technical topics.