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Always here for you
Hello! I'm the GoldenWing Assistant. How can I help you today?
Since 2021, Core Web Vitals have been an official Google ranking factor. According to Google, 73% of users measure website quality by loading speed. A slow website costs you not just rankings, but customers – Amazon calculated that every 100ms delay means 1% revenue loss.
In this guide, we'll show you step by step how to measure, understand, and optimize your Core Web Vitals – with practical tips we've successfully implemented in dozens of client projects.
Core Web Vitals are three specific metrics that measure your website's user experience:
What it measures: How long it takes until the largest visible content block is loaded (usually an image or text block).
Rating:
Why it matters: LCP shows when users can see the main content. Slower LCP = higher bounce rate.
Important: Since March 2024, FID has been replaced by INP. INP is stricter and measures responsiveness across the entire session.
What it measures: How quickly the page responds to user interactions (clicks, taps, keystrokes).
Rating:
What it measures: How much elements on the page shift during loading (e.g., when images or ads load in).
Rating:
Why it matters: Layout shifts are extremely frustrating – e.g., when you want to click a button and suddenly an ad appears.
"Speed is a feature, not a luxury. Users expect sites to be fast, and slow sites lose customers." — Addy Osmani, Engineering Manager at Google Chrome
There are several tools to check your values:
The most important tool. At pagespeed.web.dev enter your URL and receive Lab Data (simulated) and Field Data (real user data from Chrome UX Report).
Pro tip: Field data is more relevant for Google because it reflects real users. Lab data helps with debugging.
Under "Core Web Vitals" in Search Console you can see which URLs have problems. Google categorizes your pages into: Good, Needs Improvement, Poor.
Open Chrome DevTools (F12), switch to "Lighthouse" and run an audit. Ideal for detailed technical analysis.
The Web Vitals Extension shows real-time values while browsing.
Largest Contentful Paint is often the biggest problem. Here's how to improve it:
Images are usually the culprit. Our image optimization guide shows the details, here's the short version:
Time To First Byte should be under 200ms:
CSS for the "above the fold" area should be directly in HTML, not in external files. Tools like Critical CSS Generator help with this.
JavaScript and CSS that block rendering delay LCP:
Web fonts can significantly affect LCP:
Every external script costs performance: analytics, chatbots, social media widgets, retargeting pixels... Ask yourself: Do I really need this?
At GoldenWing we use Next.js and React Server Components for optimal performance. This website has an LCP under 1.5 seconds.
Since March 2024, INP is the new standard. Here's how to optimize it:
Don't load all JS code at once. Dynamic imports and route-based splitting help.
JavaScript tasks over 50ms block the main thread. Break up large calculations with requestIdleCallback or Web Workers.
Event handlers should be fast. Offload heavy operations to requestAnimationFrame or setTimeout.
Load third-party scripts in iframes or with Web Workers to relieve the main thread.
Every <img> should have width and height attributes. Modern browsers then reserve space before the image loads.
For ads, embeds and dynamically loaded content: Reserve fixed areas with min-height.
With font-display: optional or swap and size-adjust you prevent font-related shifts.
Use transform and opacity instead of width/height for animations. CSS containment (contain: layout) also helps.
You can implement these optimizations today:
When we migrated our own website to Next.js 15, we drastically improved Core Web Vitals:
Before (WordPress):
After (Next.js 15):
The result: Better Google rankings, lower bounce rate and faster page views. If you want similar results, talk to our SEO experts.
Google has confirmed that Core Web Vitals are a ranking factor – but how strong?
The truth: Content quality and relevance are still more important. But between two similarly relevant pages, the faster one wins. Also: Good Core Web Vitals → better user experience → longer time on site → better rankings. A cycle.
Our advice: Don't obsess over perfect scores, but don't ignore them either. All three metrics in the "green zone" should be your goal.
Field Data in Chrome UX Report is updated monthly but is based on a 28-day rolling window. Changes need 4-6 weeks to show in the data.
Lab data is measured under ideal conditions. Field data comes from real users with slow devices, poor internet, or many tabs. Optimize for slower devices.
Google rates pages where at least 75% of users have good values as "passing". Aim for: LCP <2.5s, INP <200ms, CLS <0.1
Yes, Google evaluates Mobile and Desktop separately. Mobile values are often worse due to slower processors and networks. Prioritize Mobile.
Absolutely. Every third-party script can delay LCP, worsen INP and cause CLS. Load such widgets delayed and outside the critical path.
For SEO, all three are relevant. For user experience, LCP is often most noticeable (slow loading annoys most). CLS is less frequent but extremely frustrating when it happens.
Difficult. Page builders generate a lot of JavaScript and CSS. You can optimize (lazy loading, caching), but will never be as fast as a custom-developed solution. For performance-critical projects, we recommend professional web development.
Need help with Core Web Vitals optimization? Contact us for a free performance analysis of your website.
We bring the same dedication and expertise you see in our articles to every client project.
“Speed is not a feature, it's a fundamental requirement.”
“A 100-millisecond delay in load time can decrease conversion rates by 7%.”
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