The Complete Guide to Google’s Core Web Vitals Performance Metrics

By James Tredwell on May 30, 2021

Most SEO experts use analytics tools and performance metrics for optimization. Better analysis leads to better search rankings, and you’re aware of insights and other ranking factors. You’ll be able to compare two to three different websites that will give you room for improvement. But how does Google access the performance of the website?

Well, it takes into account core web vitals. Core web vitals are factors that it considers most important. It covers three user interaction measurements – First input delay, Cumulative layout shift, and the Largest contentful paint. In short, core vitals are subsets of many factors that are a part of Google page experience score.

Why are Core Web Vitals so Important?

Page experience is an official ranking factor for Google. Many metrics make this up – Mobile-friendliness and responsiveness of the web page with HTTPS, which provides security. Safe browsing means having no malware on your web page.

Core vitals are an important part of the score, taking into account all the above metrics. Over the years, it has taken over to be the biggest chunk of web page score. That said, a great score will not push you to the number one spot on SERP. It only gives you a medium to reach there.

Let us break down all the three core web vitals performance metrics:

First input delay (FID)

The first input delay measures the page responsiveness. It shows how quickly pages will respond to the user’s action. It records the exact time from when the user interacts with the page. It takes into account all the taps, key presses, and clicks.

A delay of less than 100ms is good, but anything above the score of 300ms is poor. It shows the correct measurement when the application reaches the user. It only measures the real delay, and it does not consider the time taken to run or update the UI. It is dependent on the device capabilities and processor speed of the page. Render blocking assets such as – JavaScript and CSS or long-running tasks are common causes of poor FID.

Tips to improve your website’s FID score:

  • You need to remove non-critical third-party scripts. Like the FCP, many third-party scripts like – heat maps and Google analytics can affect the total score of first input delay.
  • Use a browser cache as it helps to load the content on your page faster. It will help your user’s browser blast through the JS, which will load the task at jet speed.
  • You need to minimize or defer the JavaScript support. The users can’t interact with the page when the browser loads to JS. When you reduce the Javascript on your page, it plays an important metric to improve the first input delay.

Largest contentful paint (LCP)

The largest contentful paint measures the loading performance. It shows how quickly the content appears on the page. It’s the time taken from clicking on a link and reaching the actual content on the page. It reports the time rendered for the largest image or the text block.

A time of 2.5 seconds is generally good, but anything above 4 seconds is poor. Resource loading times and server response times affect LCP. It is affected by the client size processing times and render-blocking JavaScript or CSS. You’ll be able to check the LCP score using the Google PageSpeed Insights. Improving the LCP score is not easy as installing a CDN, for you’ll have to make some extra effort.

Tips to improve your website’s LCP score:

  • Try to set up a lazy loading that will make images load when a user scrolls down your page. You can achieve a high LCP score with this.
  • Remove all the unnecessary third-party scripts as they slow down the page by 34ms.
  • You need to upgrade your web host. Faster hosting means faster loading time.
  • Remove all the large page elements. Google PageSpeed Insights will let you know about those elements.
  • Use a Content delivery network to route all the requests made by closer servers.
  • Optimize the server response by rendering server virtualization.
  • Minimize the file size of assets and CSS that can delay the LCP times.

Cumulative layout shift (CLS)

Cumulative layout shift measures visual stability. It shows the unexpected movement of content when someone views a page. It helps to access situations when the content moves without warning. CLS is calculated by multiplying the impact fraction.

It considers the total area of unstable elements in the viewport where an impact fraction of 0.5 indicates element total where half of the viewport is displaced. On the other hand, the distance fraction is the distance moved by a single element in the viewport. Here a fraction of 0.25 indicates that one element is moved by a quarter of the viewport either vertically or horizontally.

Tips to improve your website’s CLS score:

  • You need to make sure that the element of the ads have a set of reserved spaces on your website. If you don’t do this, it may suddenly appear on the page, pushing the main content down or to the other side of the website.
  • Use the set side dimensions or other attributes for the media on the page. Set separate attributes for images, gifs, infographics, and video. The user’s browser will know how much the page element will take, and it won’t change as the page loads. Try reserving an area for images and video by adding HTML height and width attributes.
  • If possible, add the new UI elements below the fold. It does not push the content to the page, and the user experience is enhanced.
  • Use the CSS aspect ratio properly to reserve the required space.
  • Don’t insert unnecessary elements towards the top of the page. Pre-size the container elements for slow loading and third-party content.
  • Use CSS transform and opacity for great animations, which do not trigger a re-layout. Also, use the common and available OS fonts on the page.

In Short,

You need to consider the many performance priorities in the core web vitals. Tackle all the quick problems first and then take the second route. Activate the server compression and ensure browser-caching function. Preload the assets and remove all unused assets.

Consider using a specific content delivery network so that it does not affect the loading time of the page. If the server is near, the loading time is faster. Don’t forget to use appropriate image size formats, and it should not affect the loading speed of the page. Optimize different elements of the page, including the content.

This article is contributed by Sudhir Bhushan – is a Tech & Social enthusiast and Founder of Bhicoupons.

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