How To Use Chrome UX Report To Improve Your Site Performance


Measuring success in website performance is a tricky task for small business owners.

It can be easy to apply the same approach that works when evaluating viability throughout a company.

Black and white, hard and fast numbers. Results.

The truth of website performance is more of a multilayered exploration of RUM (Real User Measurements) within the context of the web at large.

Looking at RUM such as performance, page load, and page views gives a detailed picture of hard data.

However, RUM data is only part of a bigger equation to measure a website’s impact and success.

The CrUX Of The Matter: The State Of The Web As Experienced By Real Users

To be truly informative and deliver actionable data, you must balance users’ experiences on your site within the scope of user experience across the internet.

Stepping back lets businesses understand their site’s performance and know where those metrics land within a vast array of parameters.

This is where the Chrome UX Report enters the fray.

Making Web Performance Data On A Broad Scale Accessible To The Masses

First established by Google in 2017, the Chrome UX Report is a publicly available dataset of real user measurements.

Also known as the CrUX report, it gathers website performance data for Chrome users from millions of websites.

If that data were only compiled, it would be an incredible – but difficult to utilize – resource. When paired with the right program, however, the data is transformed.

When put to use correctly, the CrUX Report transforms an immense collection of web performance data into a clear and accessible resource.

To better understand the data compiled in the CrUX Report and how best to utilize it, we need to step back.

It’s time to review Chrome’s Core Web Vitals.

Page Experience And User Experience Are A Direct Result Of The Health Of A Website

Google is always seeking innovative and cutting-edge ways to provide users with a smooth, crisp online experience.

A significant cornerstone of that effort is Google’s work empowering website owners to maximize their sites.

When website owners deliver user-friendly, beneficial sites effectively, everyone wins.

The only way to achieve success in an endeavor, though, is to know what the rules and standards are.

In May 2020, Google released a new set of metrics to help evaluate website performance as it impacted user experience.

These were its Core Web Vitals.

The goal was to clear away minor and arbitrary details muddying up the water.

To do so, Google narrowed down a website’s user experience score to three core measurements:

  • LCP (Largest Contentful Paint).
  • FID (First Input Delay).
  • CLS (Cumulative Layout Shift).

Core Web Vitals are anchored on the crucial role of page experience in the more extensive user experience.

How does Google define page experience?

For its purposes, page experience measures how users perceive their experience interacting with an individual web page.

Building off of that, they define CWV as:

“A set of real-world, user-centered metrics that quantify key aspects of the user experience. They measure dimensions of web usability such as load time, interactivity, and the stability of content as it loads.”

When merged, the three elements of Core Web Vitals – LCP, FID, and CLS – deliver powerful insight.

As a whole, CWV results provide a precise picture of a user’s page experience on an individual website.

This page experience ultimately defines their user experience as a whole when utilizing the Google search engine.

A year after the initial announcement, it was made permanent.

Google finalized the integration of the new metrics with the permanent inclusion of Core Web Vitals into its algorithm.

Core Web Vitals zero in on website speed, responsiveness, and visual stability. However, it should be noted that they are part of a vast picture.

The Google search algorithm is always evolving, a challenge that demands vigilance on the part of professional SEO operators.

There were once reportedly more than 200 ranking factors.

Nowadays, some are weighted far more heavily and studied throughout the industry.

These factors continue to evolve as Google adapts to new data and user behavior.

The best practice is to review its ranking factors on a year-to-year basis.

Breaking Down The Google Search Algorithm

Despite the blanket of lore that has covered it over the years, the Google search algorithm has a definitive foundation.

It is anchored by the company’s commitment to ensuring a smooth and efficient search experience for all users.

Google continuously molds its search algorithm year-round to best meet the present and future demands of the global population.

The Google search algorithm focuses on a litany of factors that perpetually fluctuates.

In response, the SEO industry has consistently honed in on the key elements to focus on every year.

Knowing where to prioritize your focus when designing your website empowers you to achieve an optimal presence in the rankings.

These can include, but are not limited to:

  • Core Web Vitals.
  • High-Quality Content.
  • On-Page Optimization.
  • User Engagement.
  • Link Building/Domain Authority.
  • Effective Keyword Strategy (Meta Title Tags).
  • Mobile-Friendliness.
    • Mobile versions given priority.
  • Search Intent.
  • Internal Links.
  • Video Search (including Clip Markup and Seek Markup).
  • HTTPS Site Security.
  • Featured Snippets.

A Deep Dive Into Core Web Vitals

It is great to understand the roles of page and user experience in forming the metrics that comprise CWV.

For those seeking to maximize the Chrome UX Report for the benefit of their companies, a comprehensive understanding is crucial. It is important to understand the roles of the individual elements of the CWV.


  • Largest Contentful Paint measures the loading performance of a page.
  • The LCP metric quantifies this by evaluating the amount of time it takes to load the largest piece of content (video, image, text block, etc.) from the moment a user requests the URL.
  • Google recommends that websites keep LCP under 2.5 seconds for 75% of their page loads.


  • First Input Delay measures the interactivity of a page.
  • More precisely, it is the time between an action to when a browser responds to that action.
  • From the moment a link, button, or other actionable element is clicked to the precise moment the page responds, transforming the webpage from static to interactive.
  • Google recommends that websites keep their FID under 100 milliseconds for 75% of page loads.


  • Cumulative Layout Shift measures every layout shift that occurs across a site.
  • It begins with zero (no shifting), increasing to a positive number (in correlation with the total amount of shifting).
  • Factors that result in shifting range from the appearance of buttons, images that force a text block to move, and dropdown banner ads.
  • Google recommends websites strive for a CLS score of 0.1 or less.
  • Boiled down to a central doctrine, one could argue simply: Speed wins.
  • In the context of the user experience, a website’s performance is integral; it is judged and measured with precision.
  • This is the crux of the SI (Speed Index) metric: How quickly the content of a page is visually displayed.
  • The speed of delivery and the performance of the information/content delivered have an extremely short window to win over users.
  • SI scores reward those pages that load a lot of data in the shortest amount of time, resulting in a better user experience.

Perception & The Unique Relationship Of LCP & CLS

Anyone who has ever interacted with a web page knows the pain of waiting for a website to load fully.

For seasoned internet veterans, the truly difficult memories rest in the dreaded dial-up era.

Those who survived those dark times could hear the America Online (AOL) internet connection sounds in their sleep.

America is experiencing the gradual rollout of 5G mobile networks and 5G wireless internet.

As a result, lightning-fast speed impacts every aspect of modern life; speed is the expectation.

When a visitor experiences significant lag time waiting for your website to load, this has severe consequences.

It negatively impacts their perception of your brand and often causes them to leave entirely.

In Google’s efforts to define page performance’s inner workings, the content load process carried significant influence.

LCP may sound intimidating, but it’s fairly straightforward.

At its core, it asks: How quickly is the most meaningful content of a web page loaded?

This content can include various elements, including images, image tags, video thumbnails, background images with CSS, and text.

LCP highlights the importance of user perception.

When does a web page first begin to matter to a visitor? When the most visible, meaningful element appears.

The gap between when a user first clicks to initiate a page and when they first see core content can feel like an eternity.

Given the immediate and critical nature of this first interaction, Google recommends an individual page’s content loads in 2.5 seconds or less.

Concentrated effort to minimize LCP allows visitors to see and experience a website faster!

And this is great.

It’s foundational to a quality user experience and rightly earns its place as one of the Core Web Vitals. But what then?

If the website that loads for the visitor is a frustrating interaction, the promise of that pristine LCP is negated.

Here, the user experience event measured as CLS makes itself known.

Similar to LCP, user perception is central to the importance of CLS.

CLS quantifies the perceived visual stability of a page, measuring how much a page unexpectedly shifts throughout the lifetime of the page.

The focus here is on the totality and extent of unexpected shifting a visitor experiences.

Regardless of how long a visitor spends on a page, they should expect a smooth experience without repetitive, jarring adjustments.

Whether it’s a brief snippet of news or an in-depth analysis that requires significant scrolling, the results should be the same.

Equally important, both websites deserve to be judged fairly, as well.

To ensure this, Google created a way to highlight key layout shifts, developing a unique system.

This system involved, among many factors, session windows, session gaps, and layout shift amounts.

The result of Google’s ongoing efforts is a metric that shines a much-needed light on what is a massive part of a visitor’s experience.

Image Optimization Is Central To LCP & CLS Strategies

Optimization efforts for LCP and CLS highlight the necessity of understanding and implementing Image Optimization.

When you review techniques that help improve results for either metric, a consistent pattern emerges.

To deliver a website with quality Core Web Vitals, owners must be purposeful in their approach.

They need to intentionally focus on managing the specific details of image and video files and the timing of their integration.

Largest Contentful Paint

  • Image optimization, including size, compression, format, and attributes.
  • Streamlined utilization of CSS and JavaScript
  • Optimal ratio of server-side and client-side rendering.
  • Top-shelf server response time.
Cumulative Layout Shift

  • Specify width + height attributes for images and videos.
  • Properly integrate content (i.e., ads and embeds) with effectively-timed JavaScript
  • Understand best practices to navigate web fonts.
  • Navigate page changes with expected layout shifts.

The Importance Of Image Optimization For LCP

Image optimization and compression are particularly important factors impacting LCP.

This is especially true for website owners unable to adjust their server response time.

Image optimization focuses on utilizing the most effective attributes for images.

This includes optimal size and resolution and capitalizing on cutting-edge file formats.

The latest and most effective image format is Google’s WebP, which delivers optimal lossless and lossy compression for web images.

WebP image compression plugins and manual pre-upload converters are often free and easy to use.

Width & Height Attributes Are Critical Factors In Preventing Cumulative Layout Shift

Few things are as aggravating as content shifting unexpectedly when a visitor attempts to read the information on a website.

It often seems that the browser is waiting for the perfect moment to strike, right when they’ve become engrossed.

Suddenly, a jarring shift occurs, and they are left to figure out where their spot shifted.

This experience will consistently and negatively impact a user’s experience, leading to increasingly difficult odds of retaining them.

Setting proper attributes is a simple but extremely effective step a website owner can take to prevent CLS.

By setting Width and Height attributes for images and videos, they preemptively restrict the browser to specific guidelines.

Without declared Width and Height dimensions, there is little instruction ensuring the visual content doesn’t cause havoc when loaded.

With responsive images, the impact of setting max-width with CSS is amplified.

This measure applies to ad images and videos, highlighting the importance of reserving sufficient space for ads in CSS.

Taking the time to constrain ad content effectively ensures it doesn’t shift a page that has already loaded.

Optimizing CWV Performance To Maximize The CrUX Report

Business leaders don’t just want their websites to perform at peak page proficiency. They want to ensure it will attract and effectively hold onto visitors.

  • It’s easier to turn off a potential site visitor than to find a debate raging somewhere on social media.
  • Today’s internet users are increasingly mobile-centric and expectant of lightning-fast speeds.
  • To not only survive in that world but to thrive, leaders need to understand Core Web Vitals.
  • They need to grasp the interlocking elements of Core Web Vitals and how they impact performance.
  • Once armed with that knowledge and understanding, leaders are equipped to maximize the benefits of the CrUX Report.
  • It’s easy to see the benefits of letting the CrUX Report speak into and guide best practices.

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