Core Web Vitals Quick Wins (LCP, INP, CLS)

Google's Core Web Vitals measure how fast your website feels to real users. If your pages load slowly, shift around while loading, or feel sluggish when clicked, you're failing Core Web Vitals—and losing visitors before they even see your content.

The good news: you don't need to be a developer to improve these scores. Most Core Web Vitals quick wins are simple fixes that take 20–60 minutes to implement. This guide covers the highest-impact changes you can make today to improve LCP (loading speed), INP (interactivity), and CLS (visual stability).

No theory. Just practical fixes that work.

What Core Web Vitals actually are (in plain English)

Core Web Vitals are three performance metrics Google uses to measure user experience:

• LCP (Largest Contentful Paint): How quickly the biggest visible element loads. Usually your hero image or headline. Google's commonly referenced "Good" threshold is around 2.5 seconds. If your LCP is 4+ seconds, users are staring at a blank or half-loaded page.
• INP (Interaction to Next Paint): How quickly your page responds when someone clicks, taps, or types. Google's commonly referenced "Good" threshold is around 200 milliseconds. If your INP is 500ms+, buttons feel laggy and frustrating.
• CLS (Cumulative Layout Shift): How much your page jumps around while loading. Google's commonly referenced "Good" threshold is around 0.1. If text suddenly shifts down when an image loads, or buttons move right as you're about to click them, that's bad CLS.

Google measures these on real users' devices (not just lab tests), which means mobile 4G performance matters more than your desktop scores on office Wi-Fi.

Quick wins that usually improve LCP

Fix the biggest image/hero

Your hero image is almost always your LCP element. If it's massive, uncompressed, or lazy-loaded, your LCP suffers.

• Compress your hero image using TinyPNG, Squoosh, or ImageOptim (aim for under 200KB)
• Serve it in WebP format (20–30% smaller than JPEG with no visible quality loss)
• Set proper width and height attributes so the browser reserves space
• Don't lazy-load your hero image—it needs to load immediately
• Use responsive images with srcset to serve smaller versions on mobile
• Consider a slightly lower quality setting (80–85% is usually unnoticeable)

Reduce render-blocking CSS/JS

Browsers can't display your page until they download and process all CSS and JavaScript files. Heavy stylesheets and scripts delay everything.

• Inline critical CSS (the styles needed for above-the-fold content) directly in your head
• Defer non-critical CSS using media queries or async loading
• Minify and concatenate CSS files (combine multiple files into one)
• Remove unused CSS using tools like PurgeCSS or UnCSS
• Move non-essential JavaScript to the footer or defer it with defer attribute
• Eliminate render-blocking third-party scripts (chat widgets, analytics—load them after page render)

Caching and CDN basics

Caching stores static files (images, CSS, JS) so they load instantly on repeat visits. CDNs serve files from servers geographically closer to your users.

• Enable browser caching via your .htaccess or server settings (cache images/CSS/JS for 1 year)
• Use a CDN like Cloudflare (free plan works well for small sites)
• Enable Gzip or Brotli compression on your server (reduces file sizes by 60–80%)
• Cache your HTML if your site is mostly static (not suitable for e-commerce without careful configuration)

Fonts (preload, fewer weights)

Web fonts block rendering until they download. Too many font weights or styles multiply the problem.

• Preload your most important font files using link rel="preload" as="font"
• Use font-display: swap in your CSS to show fallback text immediately
• Only load the font weights you actually use
• Host fonts locally instead of loading from Google Fonts
• Use system fonts as fallbacks to minimise layout shift when custom fonts load

Quick wins that usually improve INP

Cut heavy third-party scripts

Third-party scripts are common INP killers. Each script runs JavaScript that blocks the main thread and delays user interactions.

• Audit all third-party scripts and remove anything you don't actively use
• Delay non-essential scripts until after the page fully loads
• Replace heavyweight tools with lighter alternatives where possible
• Load social media embeds on click, not automatically
• Limit the number of tracking pixels

Reduce long tasks (simple explanation)

Long tasks are JavaScript operations that take more than 50ms to run. They freeze the browser and make buttons unresponsive. Reducing long tasks improves INP.

• Split large JavaScript files into smaller chunks
• Use code splitting to only load what's needed per page
• Lazy-load off-screen functionality
• Avoid running heavy JavaScript on page load

Delay non-critical JS

Not all JavaScript needs to run immediately. Delaying non-essential scripts improves interactivity.

• Use the defer attribute on script tags
• Load analytics, chat widgets, and marketing tools after the window load event
• Move non-critical scripts to the end of the body tag
• Consider using web workers for heavy computations

Quick wins that usually reduce CLS

Set image/video dimensions

If you don't specify image dimensions, the browser doesn't know how much space to reserve. When the image loads, everything below it shifts down.

• Add explicit width and height attributes to every img and video tag
• Use aspect ratio CSS (aspect-ratio: 16/9;) for responsive images
• Reserve space using min-height if dimensions are dynamic
• Test on mobile—CLS is almost always worse on smaller screens

Reserve space for embeds/banners

Ads, YouTube embeds, Instagram widgets, and cookie banners often load late and push content down.

• Use placeholder elements with min-height to reserve space before embeds load
• Set fixed dimensions for ad slots even if the ad hasn't loaded yet
• Load cookie banners before other content if they appear at the top
• Avoid inserting content dynamically above existing content

Font loading to avoid layout shifts

When web fonts load, text can reflow if the fallback font has different dimensions. This causes CLS.

• Use font-display: swap
• Match fallback fonts using size-adjust, ascent-override, and descent-override
• Preload critical fonts
• Use system fonts as fallbacks

Common mistakes that keep scores stuck

Even small errors can tank your Core Web Vitals. Avoid these:

• Lazy-loading your hero image
• Too many font weights or styles
• Oversized images
• No image dimensions
• Render-blocking CSS from plugins
• Heavy page builders (often add significant CSS/JS bloat)
• Auto-playing videos above the fold
• Unoptimised third-party scripts
• No caching or CDN
• Testing only on desktop
• Using cheap shared hosting
• Not setting font-display: swap
• Dynamic content insertion
• Ignoring mobile performance

How to measure properly (without obsessing)

Use PageSpeed Insights for quick checks

PageSpeed Insights (pagespeed.web.dev) shows lab data (Lighthouse scores) and field data (real user measurements from Chrome User Experience Report). Focus on field data first.

Lighthouse in Chrome DevTools for deep debugging

Right-click → Inspect → Lighthouse tab. Run audits on mobile and desktop. Lighthouse gives detailed recommendations, but remember: it's a lab test.

Real user monitoring (RUM) for accuracy

Tools like Google Analytics 4, Cloudflare Web Analytics, or SpeedCurve track Core Web Vitals from real visitors.

Simple measurement routine

• Test your top 5 pages monthly using PageSpeed Insights
• Check mobile scores specifically
• Track trends over 3–6 months
• Focus on field data over lab data
• Test after making changes, but give it 2–4 weeks for field data to update

FAQ