An introduction to Core Web Vitals

Written by Sean Drury

Stats on screen

For any business with an online presence, appearing as one of the first options on the Google search results is key to attracting more visitors to your website. And, given that Google publishes information about its best practice guidelines, it’s fairly simple to create websites which appeal to it. Loading speeds, mobile optimisation and use of https are among the existing ‘page experience signals’ used to determine search rankings.

The problem is that almost all professional websites are now optimised to improve loading speeds, developed with mobile responsiveness in mind, and use https (in fact https has become more common than the original http). As a result, failing to do any of these things may push your website down the Google rankings, but doing all three won’t necessarily push you up very far.

To improve their algorithm, Google is introducing Core Web Vitals as ranking signals this year. This was originally scheduled to launch in 2020, but was pushed back due to Covid-19; May 2021 is now the expected launch date.

Following Core Web Vitals is not only more likely to attract visitors to your website, it also means they are more likely to stay. In fact, by following Core Web Vitals best practices, users are 24% less likely to abandon the website, so following these practices will give your website a boost even before it affects the search rankings.

What are the new ranking signals?

There are three new signals which are being introduced:

1. Largest Contentful Paint: How fast does it load?

This is a more developed version of the existing metric of loading speed. Largest Contentful Paint is the measurement of how long it takes for the biggest item on a page to render. This might be a video, or a high-resolution image. Anything slower than 4 seconds is considered poor; ideally, the algorithm is looking for everything on a page to load within 2.5 seconds.

2. First Input Delay: How fast is it interactive?

The days when every element on a web page had to load before the page could be interacted with are long gone. Users who are accustomed to using a mobile phone expect to be able to interact with a web page as soon as it opens. Google’s algorithm is looking for a First Input Delay of less than 100 milliseconds, although this is quite difficult to achieve.

3. Cumulative Layout Shift: How fast is it stable?

If you use a mobile phone to browse the internet, you’re probably used to seeing websites where the content jumps because of an advert or alert which has popped up after the page loads. This can be very annoying and provides a bad user experience. Cumulative Layout Shift is the time it takes for a web page to become stable, and Google’s algorithm is looking for a score of under 0.1 (the calculation is based on the size of the element and the distance it jumps).

How to measure your website's performance

Google has made it very easy to check how your website is currently performing, using reports in Google Search Console. This will show whether your website is meeting the requirements of the Core Web Vitals. Green indicates ‘good’, orange is ‘needs improvement’, and red denotes ‘poor’ performance.

Ideally everything should be green, but that’s not always possible. According to an August 2020 study, less than 15% of sites are currently optimised well enough to pass a Core Web Vitals assessment.

However, once Core Web Vitals are launched and start to have an impact on the Google rankings, there will be a drive to make sure that all new development projects pass these tests. In time, these new signals will become just as essential as the existing ones, and websites which don’t adhere to them will struggle to keep up.

Where is this going?

Core Web Vitals reward websites that are quick to load, bring in content dynamically (rather than in pages) and remain interactive at all times, rather than asking users to wait. These are all behaviours that we find in mobile apps. However, this only works for certain kinds of websites, usually those which require a lot of interactivity - for searching, sorting, ordering, booking, and so on.

For more content-led websites, the slowest part is loading the infomation from the Content Management System (CMS), which often requires a lot of database calls. However, using a CMS also makes it easy to make quick edits and allows non-technical users to manage content.

Static sites tend to be a bit faster. These use plain HTML pages generated by the CMS. This approach is less common, but it has come back into popularity of late and may continue its revival with the introduction of Core Web Vitals.

Not only does this make websites faster to load, it also reduces the technology which is active on the server. Less technology means fewer things to manage and maintain, making it easier to keep updated and secure. However, these sites can be more difficult for non-technical users to edit. Modern static site generators bring the best of both worlds - the website is edited using a user-friendly online interface, but the system then automatically generates HTML pages which are fast to load without database calls.

There are lots of tools to provide useful information about website performance and ways to improve, such as Page Speed Insights, Lighthouse, and Chrome Dev Tools. However, the data that these provide can be quite difficult to understand.

That’s where Cursor comes in. We want to create websites that provide a great experience, and Google wants to connect users to websites which provide a great experience, so it’s in everyone’s best interests for us to keep up to date with the latest developments in search engine ranking signals.

We’ll be taking Core Web Vitals into account as we develop websites throughout 2021 and beyond, helping our clients to stay ahead of the competition and high in the search rankings.

Photo by Ruthson Zimmerman on Unsplash