Understanding Core Web Vitals – performance-io India

Google introduced Core Web Vitals to guide developers and site owners in understanding the quality signals essential for delivering a great user experience on the web.

Core Web Vitals are a set of metrics from Google that help developers understand how users experience a web page. These tools were mainly introduced for developers; however, site owners should also take advantage of them because Core Web Vitals help break down the user’s real-world experience on a page.

The metrics that make up Core Web Vitals focus on loading, interactivity, and visual stability. They are known as the following:

Largest Contentful Paint (LCP): The LCP metric measures the render time of the largest image or text block visible within the viewport relative to when the page started loading. Websites should attempt to have an LCP of 2.5 seconds or less to provide an optimal user experience. Read more about Largest Contentful Paint (LCP).

First Input Delay (FID): The FID metric measures the time a user first interacts with a page (e.g. when they click a link or tap on a button, etc.) to the time when the browser can begin processing event handlers in response to that interaction. Websites should attempt to have a First Input Delay of 100 milliseconds or less to provide an optimal user experience. Read more about First Input Delay (FID).

Cumulative Layout Shift (CLS): The CLS metric measures the largest burst of layout shift scores for every unexpected layout shift that occurs during the entire lifespan of a page. A layout shift occurs whenever a visible element changes its position from one rendered frame to the next. Websites should attempt to have a Cumulative Layout Shift score of 0.1 or less to provide an optimal user experience. Read more about Cumulative Layout Shift (CLS).

Google believes Core Web Vitals play an important role and are critical to all web experiences. Google has introduced some useful tools that help developers or site owners assess a site’s performance and deliver an optimal user experience. Some useful tools from Google include:

• Chrome User Experience Report 
• Page Speed Insights
• Google Search Console (Core Web Vitals report)

Once the Core Web Vitals are measured, and areas for improvement have been identified, the next step is to optimise. The following guides offer specific recommendations for how to optimise your pages for each of the Core Web Vitals:

• Optimise LCP
• Optimise FID
• Optimise CLS

Core Web Vitals are critical metrics for understanding and delivering a great user experience; however, other vital metrics help capture a more significant part of the experience or aid in diagnosing a specific issue. Let’s take a quick look at some of the other web vitals.

First Contentful Paint (FCP): The FCP metric measures the time it takes the browser to render the first piece of DOM content (images, non-white <canvas> elements, and SVGs) after a user navigates to your page. Websites should attempt a First Contentful Paint of 1.8 seconds or less to provide an optimal user experience. Read more about First Contentful Paint (FCP).

Time to Interactive (TTI): The TTI metric measures the amount of time it takes for the content on a page to become functional and fully interactive. Websites should attempt a Time to Interactive of 3.8 seconds or less to provide an optimal user experience. Read more about Time to Interactive (TTI).

Speed Index (SI): The Speed Index metric measures the average time the content on a site takes to visually display to a user during page loading. Websites should attempt a Speed Index of 3.4 seconds or less to provide an optimal user experience. Read more about Speed Index (SI).

Total Blocking Time (TBT): The TBT metric measures the total time a page is blocked from responding to any user input (mouse clicks, screen taps, or keyboard presses). Websites should attempt a Total Blocking Time of 200 milliseconds or less to provide an optimal user experience. Read more about Total Blocking Time (TBT).

Page Speed Insights was recently updated and, on 10th May 2022, two new experimental field metrics were introduced to both the API and UI, known as Interaction to Next Paint (INP) and Time to First Byte (TTFB). According to Google, these field metrics are currently experimental but will be available for users to test. As for the future, these experimental metrics may change or disappear.

Interaction to Next Paint (INP): INP is a metric that aims to represent a page’s overall interaction latency by selecting one of the single longest interactions that occur when a user visits a page. For pages with less than 50 interactions, INP is the interaction with the worst latency. INP is most often in the 98th percentile of interaction latency for pages with many interactions. Read more about Interaction to Next Paint (INP).

Time to First Byte (TTFB): TTFB is a metric that measures the time between the request for a resource and when the first byte of response begins to arrive. Read more about Time to First Byte (TTFB).

The existing Core Web Vitals have not yet changed and can still be found listed under “Core Web Vitals Assessment”. The new experimental metric INP may be added to the Core Web Vitals, or it may replace the existing FID metrics. Read more about the potential change in Core Web Vitals.

At performance-io, we consider Core Web Vitals to be one of the most important technical aspects to directly affect website user behaviour. Based on our template, we check each aspect of Core Web Vitals and recommend suggestions to resolve any issues that may impact the user page loading experience

As a performance marketing agency, we use customised products to audit your website. These help measure how users perceive the experience of interacting with web pages beyond just the quality of the content. 

As Google evaluates page experience metrics for individual URLs on the site and uses them as a ranking signal in Google Search results, we audit each and every page of the website and provide specific recommendations. 

We focus on providing you with details and examples of issues with explanations on the level of seriousness, as well as a description of the suggested implementation of a given SEO element. 

Based on our website audit, we also provide recommendations as to whether development work may be required, its complexity (if applicable), and the time needed to implement those changes.

Our unique approach will help you understand your website’s current status and aid in improving its overall Core Web Vitals, ultimately providing an optimal user experience.