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A fundamental principle in SEO is that most effective tactics change over time. Success in search is a game where the rules are constantly changing. 

Google recently announced an addition to its core web vitals assessment. A shift that will see your website experience graded across three additional metrics; loading (LCP), interactivity (FID) and visual stability (CLS). 

Google's core web vitals

The changes stem from a belief that Google serves the best possible results to users. That means not only serving the most relevant results, but also the easiest to use, quickest to load and now, one that won’t cause frustration along the way. Google conveniently bundles these factors into “Web Vitals” – which provide metrics and guidance on what’s essential delivering a great user experience on the web.

It’s important to state that these updates are in addition to – and not replacing – existing factors around search engine optimisation on site. Links from trusted sources remain important!

Here we start to review how to begin refining a website to take these changes in account. 

(We’ll be diving deeper into this in a Cogcast digital session and longer piece of writing later in the autumn. Watch this space for updates.)

Find your baseline 

There are several ways to access Web Vitals. Finding a website’s current stats – and benchmarking them with the competition – is an obvious first step towards making improvements.

Here are the three most common ways to approach: 

  1. PageSpeed Insights: Run your website domain through Google’s free PageSpeed Insights tool. This will provide clear indications of where any issues may lie across loading, interactivity and visual stability. You’ll need to do this manually every now and then, and performance can vary depending on how website traffic during the day and month.
  2. Google Search Console: Firstly, ensure your webmaster has this setup. This is a fantastic free tool that gives you live information on the health of your website from Google’s point of view, including any penalties you may have against your domain. Invaluable! A core Web Vitals report sits inside the console. 
  3. GTmetrix: GTmetrix is a 3rd party tool, similar to Google’s PageSpeed Insights, that gives a more granular breakdown of factors impacting on site performance. While this is great for diagnosing load time, however this won’t help pick through interactivity or layout shift issues.
  4. Use Google's new tool. This is awesome for getting a general sense of website hygiene factors including performance, accessibility, best practice and SEO.

Warning signs

Cumulative Layout Shift (CLS)

CLS is new to the block. This measures the visual stability of the site. A typical example of poor CLS is when you go to a slow loading page, go to click a button and something loads above it, shifting the clickable area down the page. To provide a good user experience, pages should maintain a CLS of less than 0.1.

Example of how layout shift can frustrate a user:


Largest Contentful Paint (LCP)

LCP measures loading performance and more broadly, how quickly the site loads. To provide a good user experience, LCP should occur within 2.5 seconds of when the page first starts loading. There are a number of factors that could result in poor performance here, from server spec, server setup, caching and images size.


First Input Delay (FID)

FID measures the time from when a user first interacts with your site, such as clicking a button/link, to the time when the browser actually responds to that interaction. Typically a slow FID score can be the result of the browser’s main thread being busy parsing and executing a significant amount of Javascript or other code, after the page content has already loaded. Main culprits of this can be analytics, automation softwares such as Pardot etc.

To provide a good user experience, pages should have a FID of less than 100 milliseconds. Ensure you’re utilising Google Tag Manager so you can control what scripts load on what pages, removing those that aren’t relevant in certain areas of your site.


Advanced studies

There are a large number of ranking factors for SEO, of which site speed, performance and UX are just a few. There has been some fantastic research on the direct effect of these factors with your rankings. These factors alone won’t give you a top spot on the search results, but poor metrics will most certainly hold you back from ranking higher. 

Working with a specialist – whether in-house or consultant – can track these metrics over time as part of a larger search strategy. Through consistent, concerted effort, any website can make progress on relevant keywords and topics. 

James Hannaford is a Director at Cognito London