What Are Core Web Vitals?

Core Web Vitals are a set of performance measurements developed by Google to evaluate three important parts of the website experience.

They answer straightforward questions:

• Largest Contentful Paint (LCP): How quickly does the main content appear?
• Interaction to Next Paint (INP): How quickly does the page respond when someone interacts with it?
• Cumulative Layout Shift (CLS): Does the page remain visually stable?

These aren’t simply measurements of how clean your website’s code looks.

They reflect experiences that visitors can notice, particularly on mobile devices or slower connections.

Google evaluates Core Web Vitals using performance thresholds based on the 75th percentile of page visits, with mobile and desktop data assessed separately.

In practical terms, that means your website should deliver a good experience to most visitors, not just perform well during one test on a fast computer.

What Are the Recommended Core Web Vitals Scores?

These are Google’s recommended thresholds, not guarantees of better search rankings.

Let’s look at what each metric actually means.

Largest Contentful Paint (LCP): Does Your Page Load Quickly?

LCP measures how long it takes for the largest qualifying visible content element to render within the viewport.

That might be a hero image, a large heading, or a prominent product photograph.

Google considers an LCP of 2.5 seconds or less good.

For a business website, the importance is easy to understand.

Imagine a potential customer clicking an advertisement for a roofing company. The visitor expects to see information about roof repairs, service areas, or how to request an estimate.

Instead, the page spends several seconds loading before its main content appears.

Even if the rest of the website is beautifully designed, the first impression isn’t particularly encouraging.

What Causes Poor LCP?

Common causes include:

• Large or poorly optimized images.
• Slow server response times.
• Render-blocking CSS or JavaScript.
• Important images that begin loading too late.
• Inefficient delivery of fonts or other critical resources.

The cause matters because the solution isn’t always the same.

Compressing images won’t fix a server that’s consistently slow to respond. Upgrading hosting won’t necessarily solve an oversized hero image that the browser discovers too late.

How to Improve LCP

Start by identifying the element responsible for the LCP score.

If it’s a large image, make sure its dimensions and file size are appropriate for the display.

Modern formats such as WebP or AVIF can help reduce image transfer sizes when properly implemented.

Then check how the image loads.

Your main LCP image generally should not use lazy loading. The browser needs to discover and request it early.

Lazy loading is more appropriate for images farther down the page that visitors may never see.

If server response is the problem, investigate hosting performance, caching, and content delivery.

The goal isn’t to apply every speed optimization available. It’s to fix the delay actually affecting your page.

Interaction to Next Paint (INP): Does Your Website Respond?

INP measures how responsive a page is to user interactions, including clicks, taps, and keyboard input.

It replaced First Input Delay (FID) as a Core Web Vital in March 2024.

Google recommends an INP of 200 milliseconds or less.

Think about an online store.

A customer clicks “Add to Cart,” but nothing visible happens immediately. They click again, uncertain whether the first action worked.

Or someone opens the navigation menu on a mobile website, and it takes noticeably too long to respond.

The page may have loaded quickly, but using it still feels frustrating.

What Causes Poor INP?

JavaScript is a frequent contributor.

When a browser is busy processing lengthy tasks, it may delay responding to an interaction or displaying the result.

Potential causes include:

• Heavy JavaScript execution.
• Complex interactive components.
• Inefficient event handlers.
• Excessive third-party scripts.
• Tasks that block the browser’s main thread.
• Expensive rendering updates after an interaction.

Live chat widgets, advertising scripts, analytics tools, and other integrations can contribute to the problem.

But that doesn’t mean every third-party tool is responsible or that removing plugins indiscriminately will fix the issue.

You need to identify what’s causing the delay.

How to Improve INP

Start by testing the interactions that matter most to your business.

Try your mobile navigation, contact forms, search functions, product filters, and purchasing controls.

Then investigate slow interactions using browser performance tools.

Developers may improve responsiveness by reducing unnecessary JavaScript, breaking up long tasks, or simplifying expensive interface updates.

For WordPress websites, review installed plugins and third-party integrations, particularly those that add scripts to pages where they aren’t needed.

Don’t disable critical plugins on a live website simply to see what happens.

Test significant changes in a staging environment and confirm that forms, navigation, checkout, and tracking still work afterward.

A faster page isn’t much of an improvement if the contact form stops submitting.

Cumulative Layout Shift (CLS): Does Your Page Stay Put?

CLS measures unexpected visual movement while someone is using a webpage.

You’ve probably experienced it.

You’re reading an article on your phone and prepare to tap a link. Suddenly, an image loads above it, the content shifts, and you tap something else.

That’s the type of frustrating experience CLS is designed to identify.

Google considers a CLS score of 0.1 or less good.

Unlike LCP and INP, CLS is a score rather than a measurement in seconds.

What Causes Poor CLS?

Common causes include:

• Images or videos without reserved dimensions.
• Advertisements inserted into the page without sufficient space.
• Banners or widgets that appear above existing content.
• Fonts that cause text dimensions to change when they load.
• Dynamic elements that move other content unexpectedly.

Not every movement is necessarily a problem. For example, certain shifts directly following an intentional user interaction are treated differently in CLS measurement.

The concern is unexpected movement that interferes with the experience.

How to Improve CLS

Start with elements that change the layout as they load.

Set appropriate width and height attributes or aspect ratios for images and videos so browsers can reserve space.

Allocate predictable space for advertisements, embeds, and other content loaded dynamically.

Review web fonts and how they affect text rendering. Font-loading strategies and compatible fallback fonts can help reduce visible shifts.

Be particularly careful with banners, popups, and other components that insert themselves above content someone is already reading.

Many CLS problems are straightforward to correct once you’ve identified the moving element.

Do Core Web Vitals Affect Google Rankings?

Yes. Google confirms that Core Web Vitals are used by its ranking systems.

But there’s an important distinction between contributing to search performance and determining search performance.

Google doesn’t rank websites according to a simple formula where the fastest page automatically wins.

Relevance, content quality, and many other signals still matter.

A website with excellent Core Web Vitals but irrelevant content may not perform well in search.

Likewise, a slower page can still appear prominently if it provides information that is particularly relevant to the query.

Google specifically cautions that achieving good Core Web Vitals does not guarantee high rankings.

So why improve them?

Because a website should work well for the people using it, regardless of how search rankings respond.

The Business Value Goes Beyond SEO

Consider what happens when someone visits your website.

They need to understand your offer, navigate the page, and complete an action.

If the page is slow, buttons hesitate, or the layout shifts unexpectedly, that process becomes harder.

Fixing these problems can remove obstacles from the customer journey.

However, you shouldn’t assume every performance improvement will produce an immediate increase in conversions or revenue.

Track the outcomes that matter to your business and evaluate whether the changes have improved the visitor experience.

For a broader look at technical optimization, explore MoDuet’s SEO services.

How to Check Your Core Web Vitals

Before changing plugins, images, or hosting settings, find out what your website is actually doing.

Two free Google tools provide a useful starting point.

Google PageSpeed Insights

PageSpeed Insights analyzes a URL and provides information about its performance on mobile and desktop.

The report may include two different types of information:

Field data: Performance measurements collected from real Chrome users, when sufficient data is available.

Lab data: Results from a simulated performance test using Lighthouse.

These are useful for different reasons.

Field data helps you understand experiences occurring in the real world.

Lab data helps identify potential technical causes and test improvements under controlled conditions.

Don’t assume that a high Lighthouse performance score means every visitor is having a good experience.

And don’t be surprised when field data and lab data show different results. They measure performance under different circumstances.

Google Search Console

Google Search Console includes a Core Web Vitals report that groups URLs with similar performance issues.

Instead of investigating every page individually, you can identify patterns affecting multiple pages.

For example, poor LCP scores across a group of service pages may suggest a shared template, hosting, or image-loading issue.

The report helps identify where to investigate, but you’ll still need additional diagnostics to determine the cause.

What If Your Website Has No Field Data?

Smaller websites or individual pages may not have enough eligible Chrome user data to display URL-level field results.

That doesn’t mean performance is good or bad.

It means the available real-user data is insufficient for that report.

Use Lighthouse and other diagnostic tools to investigate performance while recognizing that simulated results don’t perfectly represent every visitor.

Which Core Web Vitals Problems Should You Fix First?

Not every warning deserves the same urgency.

Start by identifying issues that affect important pages or interrupt meaningful customer actions.

Prioritize pages that support your business goals, including service pages, contact pages, product pages, and high-traffic landing pages.

Also consider the scale of the problem.

An issue affecting a shared template may deserve attention before a minor warning on one rarely visited page.

For more information about the website infrastructure behind performance, see MoDuet’s website development services.

Core Web Vitals for WordPress Websites

WordPress makes it relatively easy to add functionality.

That flexibility is useful, but it can also create performance problems when plugins, scripts, and design features accumulate without regular review.

If your WordPress site performs poorly, don’t assume the content management system itself is the cause.

Review what’s actually happening.

Check Images and Page Layouts

Look for oversized hero images, unnecessarily large background images, and layout components that load content late.

Pay particular attention to mobile layouts, where images and design elements may behave differently.

Review Plugins and Scripts

Identify plugins that introduce substantial JavaScript or CSS.

Not every plugin has a significant performance impact, and counting plugins alone doesn’t reveal which ones are responsible.

A single poorly optimized integration can cause more trouble than several lightweight plugins.

Check Caching and Hosting

Caching and infrastructure can affect server response times and resource delivery.

If your site experiences consistently slow responses, investigate your hosting environment and caching configuration.

A CDN may help deliver certain resources more efficiently, but it isn’t a universal solution to every Core Web Vitals problem.

Learn more about MoDuet’s website hosting options.

Test Before and After Changes

Always keep a baseline.

Record the affected pages, their performance measurements, and the issues you’re trying to solve.

When possible, test significant technical changes in staging before applying them to your live website.

Then confirm that important functionality still works.

The goal is a faster, more usable website, not a beautiful PageSpeed report attached to a broken checkout.

Core Web Vitals Need Ongoing Attention

Here’s something worth knowing before you consider the job finished: Core Web Vitals aren’t static.

Website updates, new plugins, design changes, advertising scripts, and hosting conditions can affect performance.

Field measurements can also vary as traffic patterns, devices, and network conditions change.

Google’s Chrome User Experience Report provides aggregated real-user performance data. The field data displayed in PageSpeed Insights generally reflects a rolling 28-day collection period.

That means an optimization may not immediately appear in the field results, even if a new lab test shows improvement.

A practical maintenance routine should include:

• Reviewing Core Web Vitals reports periodically.
• Checking important pages after major website changes.
• Testing forms, navigation, and purchasing functionality.
• Investigating new performance warnings.
• Comparing results with a reliable baseline.

You don’t need to obsess over every fluctuation.

You do need to notice when a meaningful part of your website becomes harder to use.

A Better Website Experience Is the Real Goal

Core Web Vitals give businesses a practical way to evaluate loading speed, responsiveness, and visual stability.

They also provide useful technical priorities when a website feels slower or less reliable than it should.

But the objective isn’t to achieve a perfect score for the sake of having one.

It’s to make sure your website helps visitors understand your business and take the next step without unnecessary friction.

Start by measuring what happens today. Identify the problems affecting real users. Fix those issues carefully, and monitor the results.

Your website is working for your business around the clock.

Make sure it’s doing the job properly.