What Are Google’s Core Web Vitals, and How Can Publishers Prepare For Them?

SEO is about to experience a serious shake-up. In June 2021, Google will begin the gradual roll-out of an update to its search algorithm, with the full update coming into action at the end of August. The update introduces a new set of metrics known as ‘Core Web Vitals’ – with the potential to radically alter publishers’ existing search rankings. 

For many, these changes appear complex and overwhelming. So we’re going to explain exactly what Core Vitals mean for you, and what you can do to not just survive but actively benefit from the update

What Are Core Web Vitals?

Core Web Vitals (CWVs) are a set of technical metrics that rate the speed, responsiveness, and visual stability of a particular web page. 

These new metrics will be combined with existing metrics like mobile-friendliness and safe-browsing which are used to compare the User Experience a website offers – ultimately rewarding user-friendly pages with higher search rankings.  

This builds on Google’s 2017 report, where they found that many websites simply weren’t up to scratch in terms of User Experience: on 70% of sites, it took nearly 7 seconds for visual content to load.  

By updating their algorithm to take Core Web Vitals into account, Google hopes to incentivise businesses to improve their User Experience.  

What Are The Three Core Web Vitals Metrics?

1. Loading time

Technical name: Largest Contentful Paint (LCP) 

What it measures: How long the largest piece of visible content on a webpage takes to render relative to when the page started loading. This is usually a large image or block of text – the first thing a user is likely to see. 

The ideal LCP: Experts believe websites should aim for an LCP score of 2.5 seconds in order to rank well for this metric.  

2. Interactivity

First Input Delay (FID) 

Technical name: First Input Delay (FID) 

What it measures: How quickly a page is able to respond to the visitor’s first ‘input’. Examples of an input could be scrolling, clicking a button or any other interactive element your website features.  

The ideal FID: Research suggests an FID score below 100ms will help your rankings and be perceived by users as instantaneous responsiveness. 

3. Visual Stability


Technical name: Cumulative Layout Shift (CLS) 

What it measures: The visual stability of a page, which is determined by how frequent ‘layout shifts’ are. In essence, a layout shift is when content on a page changes position unexpectedly – like text suddenly moving, or a button dodging your attempts to click on it.  

The ideal CLS: Experts claim that a CLS score of 0.1 or less will help protect your ranking and provide a smooth, stable User Experience.  

How Do Core Vitals Affect Publishers?

In terms of SEO, it is perfectly possible that Core Vitals will not immediately impact most search rankings, as Google has already clarified that the quality of content will still be the key factor in search rankings and strong User Experience already correlates with higher ranking 

But for publishers, the story is slightly more complex. Many high-impact advertising formats that big-ticket advertisers favor produce slow load time and disrupt visual stability; many publishers currently have CLS scores 10 or 20 times higher than Google’s benchmark pass grade.  

This could lead to a nasty knock in search rankings for many publishers, ultimately decreasing their page hits and overall revenue. But there is reason to be optimistic, because improving Core Vital scores isn’t only vital for publishers’ SEO – there’s good reason to think it could benefit them in other ways, too.  

The load speed and usability of your website is directly correlated with numerous important factors, like engagement and conversionsSo improving your Core Vitals will also likely help improve your website’s Ad-Experience and overall commercial effectiveness.  

How to Review Your Website’s Core Vitals?

Google Pagespeed
PageSpeed Insights analyzes the content of a web page, then generates suggestions to make that page faster.

Before optimising your Core Vitals, you need to measure how your site currently performs. This can be done with a number of tools, which will provide your development team with insights to base their efforts on.  

Among the best are PageSpeed Insights – which is run by Google – and Web.Dev Measure. Both use Lighthouse – an open-source, automated tool that diagnoses and audits pages. You can also download Google Chrome’s Web Vitals extension, which provides real-time feedback on your website’s performance while you browse.  

When reviewing your website’s performance, it’s important to remember that pages can rank differently for mobile and desktop – so each should be reviewed and optimised for Core Vitals separately.  

How to Assess Your SEO Performance?

While understanding your Core Vital scores is important, you also need to understand how Core Vitals relate to your actual SEO performance. This is where Google Search Console comes in handy: it gives you clear, reliable data on your website’s current search ranking for various keywords, as well as locating ways to improve the page’s performance. 

Page experience is a set of signals that measure how users perceive the experience of interacting with a web page beyond its pure information value.

Using the tool requires more investment than PageSpeed Insights or Web.Dev, as you have to create an account and verify that you own the domain you are measuring. But it is well worth it to accurately and granularly track your SEO performance.  

The Google Search Console performance tab allows you to see how your website ranks for various keywords over a period up to 16 months, so you can monitor how search rankings are changing over time. You can see how many clicks your site receives on Google; how often it appears in Google searches; what its Click-Through-Rate is; and the page’s average search performance over time. 

As Core Vitals are introduced to Google’ algorithm, having a handle on this tool will be essential for monitoring how the change is impacting your SEO – and how much time and effort you should be investing in improving your Core Vitals. 

Ten Ways to Improve Your Core Vitals

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1. Remove Unnecessary Third-Party Scripts

recent study found that each third-party script – such as Google Analytics – slowed a page down by 34ms. Publishers can immediately improve their LCP score by simply getting rid of any scripts that are not essential.    

This will improve: LCP and FID 

2. Upgrade Your Web Host

Many website owners look to cut costs on their hosting, opting for cheaper options. But the truth is, better hosting really does equate to faster loading time. 

This will improve: All core vitals 

3. Set Up Lazy Loading

Lazy loading is a design pattern that enables images to load when they are needed – and not a moment sooner. This means images lower down the page won’t load until a visitor scrolls to them, enabling the initial images to load faster. 

This will improve: LCP and FID  

4. Remove Large Page Elements

Excessively large page elements – like videos or large images – may be slowing your page’s LCP. Google PageSpeed Insights will let you know which elements are most problematic, and you can replace them with small, less problematic files.   

This will improve: All core vitals 

5. Minify Your CSS

Minification is the process of minimising code and markup on websites. CSS is leaned on heavily by many publishers to style their websites, but extremely bulky CSS can significantly delay your LCP times – and minifying will solve this problem.  

This will improve: LCP and FID 

6. Minimize JavaScript

While a web page is loading Java, it is virtually impossible for a user to interact with the page elements. This means your FID will take a large hit if you have excess Java – so minimize it wherever you can. Another way of reducing its impact is by deferring unused Java by code splitting.   

This will improve: LCP and FID 

7. Use a Browser Cache

Caching immediately increases your page’s load speed, by minimizing the amount of work needed for the server to generate it. This will also help your user’s browser load Java faster – further increasing the page speed. 

 This will improve: LCP & FID  

8. Use Set Size Attribute Dimensions For Media

Whether it’s videos, images, GIFs or infographics, ensuring the user’s browser knows exactly how much space an element will take up is essential. This means it won’t change unexpectedly as the page loads, creating a smooth experience for the user.  

This will improve: CLS 

9. Make Sure Ad Elements Have a Reserved Space

If ads don’t have a fixed position, they can suddenly appear from nowhere and push content down or across – which creates a very irritating experience for the user. Not only does having reserved space create a better User Experience – it creates a better Ad Experience.  

This will improve: CLS 

10. Add New User Interface Elements Below the Fold

Like ads, new User Interface elements can disrupt content, pushing it down the page. By adding it below existing content, you avert this risk and ensure new content elements can be added with disrupting your User Experience – or your SEO ranking! 

This will improve: CLS 

 How can Project Agora help ?

At Project Agora, we provide publishers with a 360 Tech Stack that gives them everything they need to maximize their advertising revenue. 

But we also understand that SEO is essential for publishers. So, we are working proactively to improve the load speed and optimize the performance of our ad experiences – creating smoother page experiences and helping our partners achieve exceptional Core Vital results. 

We are doing this in a number of ways: 

  • We use a Content Delivery Network (CDN) to optimize the time our assets take to load  
  • We use the latest web browser APIs to improve page speed and stability 
  • Our code is split following the module architecture, ensuring that it is scalable and stable 
  • We use the async technique to ensure assets load without interrupting from other executions 
  • Our AdTag logic is lightweight and faster rendering, allowing the thread to properly continue its processing 
  • We are minifying our JavaScript code, allowing the browser to handle parsing and execution more easily 
  • And we deliver mobile friendly formats for better User Experience 

In combination, these measures are helping us adapt confidently to Google’s update – ensuring our partners can respond smoothly to the changes and stay ahead of the competition.  If you would like to learn more on our Publisher monetization solutions, you can contact us today to speak with one of our experts.