What We Learned About Core Web Vitals

This post was sponsored by SearchmetricsThe opinions expressed in this article are the sponsor’s own.

The SEO community has been buzzing about the upcoming Core Web Vitals update, which is due to roll out in mid-June.

This new Google algorithm update puts the spotlight on user experience.

Three Core Web Vitals (CVW) metrics – Largest Contentful Paint, First Input Delay, and Cumulative Layout Shift – will assess critical elements of user experience including visual stability, loading experience, and interactivity.

This performance will be then used as a ranking signal and is expected to affect page rankings.

But for many, this update raises more questions than answers:

  • Do I need to change anything on my website to get ready for this update? If so, what?
  • Is Google going to immediately downgrade rankings for websites with poor CWV scores?
  • How well are competitor websites performing in terms of CWV? What benchmarks should I aim for?
  • Are other ranking factors interconnected with my Core Web Vitals score?
  • How easy is it to optimize websites created with builder/CMS platforms such as WordPress or Wix?
  • Do Google’s entities (e.g., YouTube) perform well in Core Web Vitals?

At Searchmetrics, we wanted to dig deeper and find data-driven answers to these questions.

We analyzed over 2 million URLs across the Core Web Vitals and further metrics to understand:

  • How websites are performing.
  • Whether Google’s benchmarks are realistic and useful for businesses.

You can read the study here.

But before we dive into the data, let’s understand what Core Web Vitals are and, more importantly, the logic behind them.

What Are Core Web Vitals & Their Benchmarks?

There are three Core Web Vitals metrics:

3 Core Web Vitals metrics illustration

Largest Contentful Paint measures the render time of the largest image or text block visible within the viewport. The key idea is to provide a simple metric that shows how quickly a page’s main content loads.

To provide a good user experience, LCP should occur within 2.5 seconds of when the page first starts loading.

First Input Delay measures when a user first interacts with the page.

To provide a good user experience, pages should have an FID of less than 100 milliseconds.

Cumulative Layout Shift is a score that measures how much content shifts during page rendering. A lot of content shift creates a negative user experience.

To provide a good user experience, pages should maintain a CLS of less than 0.1.

Web Core Vitals metrics for loading, interactivity and visual stability

What Is Google Trying to Accomplish with Core Web Vitals?

According to Google, this update has two main purposes:

  • To increase Google’s emphasis on user experience. In simple terms, if a user has a good experience on a webpage, Google aims to rank this page higher.
  • To make it simpler for brands and businesses to understand website performance and improve the user experience.

Why now?

We live in a world where users want to enjoy high-quality content as smoothly as possible across all devices. But are websites delivering?

We all know how frustrating it is to quickly search for a news article only for the page to take forever to load. When you finally get there and scroll or click on something the page shifts as an ad banner tries to sell you something.

Not ideal.

The Google Core Web Vitals update is in many ways a response to websites not living up to user expectations. It’s a clear message that not putting users first may have a negative effect on your rankings.

What Is Causing Poor Web Performance?

There are many factors causing poor web performance.

In many ways, slow loading times are a symptom of what has become standard practice for creating a website.

Website-Building Platforms

Rather than custom building something, businesses are increasingly turning to website builders such as Squarespace or Wix to save time.

The problem is, while such website builders are easy to use on the surface, they can be tricky to optimize under the hood.

Often, webpages designed using these templates load all scripts, stylesheets, and code blocks even if they are not needed.

This can cause what is known as code bloat – where unnecessary code is loaded on a webpage causing slow page loading times.

Plugin-Centric Web Economy

The logic of a platform like WordPress is also plugin-centric.

This means that if you need to do something beyond adding basic content, such as optimizing images or lazy loading below-the-fold content, then you will need to use a plugin.

These plugins are quick solutions but are another source of code bloat.

Ad Space & Dynamic Content

Another key cause for poor user experience is dynamic content.

Dynamic content, like ads, can cause a lot of layout shifts if not properly implemented. The same is true for newsletter opt-in boxes and any dynamic content.

So does this perceived poor performance play out in the data?

Searchmetrics’ CWV Study: A Sneak Peek

Searchmetrics’ study on Google Core Web Vitals revealed that less than 4% of U.S. websites we analyzed achieve a “good” score in all three Core Web Vitals.

Searchmetrics CWV study: Only 4% of websites achieved a

Searchmetrics CWV study: Ove
rview of Top 5 and Top 20 performance averages


While sites ranking in the top 5 Google search positions performed marginally better than those outside, they still had the same overall performance issues.

Websites Lack Visual Stability

The biggest stumbling block was visual stability, measured by Cumulative Layout Shift. Few websites achieved a good score in this metric.

We found the top 20 average CLS to be 0.38, well above Google’s good threshold of 0.1 and even outside the moderate threshold of 0.25

This is explained by the rise of dynamic content such as ad placements, newsletter subscription boxes, and websites not reserving space in the layout for these elements.

Code Bloat Is Real

Considering how many websites have been created by platforms such as Squarespace and Wix, our data confirms that code bloat is a real issue.

On average, Google’s top 20 U.S. websites could save around 1 second in page load time simply by removing unused JavaScript.

Images & Videos Are Still Poorly Optimized

A primary cause of slow loading times was large asset files such as images and videos. Websites should aim to defer loading of any below-the-fold assets and only focus on what is necessary.

Using next-gen formats like Google’s WebP can also result in a substantial reduction in asset size.

What About YouTube?

We also filtered out YouTube from the results. Interestingly, we noticed a significant improvement in metrics connected to load time.

This means that YouTube performs poorly in metrics like Largest Contentful Paint.

As an asset-heavy website, this is to be expected, however, YouTube manages to overcome this and still ranks highly.

Are Google’s Core Web Vitals Benchmarks Realistic?

We analyzed Core Web Vitals performance for both desktop and mobile and we believe that – perhaps surprisingly – the desktop values provide a better benchmark to aim for.

But why is this?

Google throttles data to emulate a mid-range mobile device when analyzing mobile performance.

However, this leads to slow times that are not necessarily reflective of the current state of the mobile web. We go into this in detail in the study.

So is it fair to punish websites for poor Core Web Vitals scores?

Google’s effort to make user experience metrics more transparent could help businesses objectively QA their sites while under development.

Rather than requesting features and design elements, businesses could brief Core Web Vitals targets that web developers need to hit.

However, this is harder to imagine for out-of-the-box web builders like Wix and WordPress.

They often rely on loading many different dynamic layout elements and using JavaScript plugins to accomplish relatively basic tasks.

To stay competitive, these platforms will need to up their game in terms of helping websites meet user experience targets and offering transparent ways to optimize website performance.

Will Core Web Vitals Affect Rankings in June?

This is the million dollar question.

With so many websites performing poorly in the Core Web Vitals, it would seem unlikely that Google would punish business across the board.

However, our analysis should serve as a reminder that user experience currently isn’t good enough on most websites.

Tackling this issue now, along with web development best practices that place the user center stage, will be beneficial in the long term.

It’s tricky to predict exactly how much Google will use Core Web Vitals scores to determine rankings, but it is certain that websites with excellent user experiences will have a crucial competitive advantage.

A good user experience sends good user signals to Google which does boost rankings.

Get instant access to all the findings, benchmarks, and insights in the most comprehensive Core Web Vitals study of its kind.

Image Credits

Screenshots #1 & 2 from Google.
All other images by Searchmetrics. Used with permission.