Understanding Google's Core Web Vitals

In May 2021, Google began taking Core Web Vital scores into account when determining search rankings. Core Web Vital Scores can be leveraged to improve your site's search engine optimization. The information below is taken from web.dev , Google's web development knowledge base. You can learn more about Core Web Vitals here and here.

Key Metrics

Largest Contentful Paint (LCP) applies to load time. LCP measures how long it takes from the time the page begins loading for the largest image or block of text in the viewport to render. The target LCP time is typically less than 2.5 seconds.

First Input Delay (FID) applies to user interaction. FID measures how long it takes from the time a user first interacts with the page for the browser to start processing event handlers. The target FID time typically is less than 100 milliseconds.

Cumulative Layout Shift (CLS) applies to how stable the visual components of a page are. CLS measures the most significant layout shift score burst for each layout shift that occurs unexpectedly. The target CLS score typically is less than 0.1.

Lab Data and Field Data

Google offers tools to obtain both lab data and field data on your Core Web Vitals.

You can collect field data to assess the performance of features after they've been released to real-world users. All Core Web Vitals ultimately represent field data.

You can also use lab data to assess features as they're being developed and catch regression issues before they occur.

Important:

Though valuable, lab data does not capture the full scope of site performance or user experience, or what contributes to your overall page experience score. Field data is largely more accurate and holistic.

Low scores based on lab data are not necessarily indicative of poor page performance in the field (i.e, when a real end-user visits the page).

Using Query Parameters to Hide the Banner

You can use the query parameter hidebanner=true to load webpages without your consent banner displaying and produce a more realistic view of your page loading for your website users.

In field scenarios, your banner likely does not appear on every webpage. The user consents and the banner is no longer shown until consent expires or you prompt for re-consent. Hiding the consent banner enables you to run pages through Lighthouse without your banner loading, which allows you to more realistically analyze your core web vitals.

If your Core Web Vitals scores are still low with the consent banner hidden, consider other ways in which you can optimize your pages.