Google's Core Web Vitals directly impact your search rankings and user experience. If your site scores poorly on Largest Contentful Paint (LCP) or Cumulative Layout Shift (CLS), you're losing visitors and potential customers. Slow loading times frustrate users. Unexpected layout shifts irritate them. Both drive people away from your site.
This guide shows you exactly how to fix Core Web Vitals issues and improve your LCP and CLS scores. You'll learn what these metrics measure, why they matter for Australian businesses, and practical steps to optimise your website. Every technique here is tested and proven to work in 2026.
Understanding Core Web Vitals
Core Web Vitals are three specific metrics Google uses to measure user experience on websites. They focus on loading performance, interactivity, and visual stability.
Largest Contentful Paint (LCP) measures how quickly the main content of your page loads. Good LCP scores are under 2.5 seconds. If your largest visible element takes longer to appear, users perceive your site as slow.
First Input Delay (FID) measures how quickly your page responds to user interactions like clicks or taps. Google is replacing FID with Interaction to Next Paint (INP) in 2024, which measures responsiveness throughout the entire page visit.
Cumulative Layout Shift (CLS) measures visual stability. It tracks unexpected movement of page elements while loading. Good CLS scores are under 0.1. When buttons move or text shifts as a page loads, users accidentally click the wrong elements or lose their reading position.
These metrics matter because Google uses them as ranking factors. More importantly, they directly affect whether visitors stay on your site or leave immediately. Poor Core Web Vitals result in higher bounce rates, fewer conversions, and lost revenue.
Why LCP and CLS Matter Most
While all three Core Web Vitals are important, LCP and CLS cause the most problems for Australian businesses.
LCP issues are extremely common. Most websites struggle with large images, render-blocking resources, or slow server response times. Every extra second of load time reduces conversions significantly. Users expect pages to load instantly, especially on mobile devices.
CLS problems create frustrating experiences. Imagine clicking a button just as an advertisement loads above it, shifting everything down. You accidentally click the ad instead. This happens constantly on sites with poor CLS scores. Users associate this frustration with your brand.
Fixing these two metrics delivers the biggest impact on user experience and business results. Focus here first, then tackle other performance issues.
Diagnosing Your Core Web Vitals Issues
Before fixing problems, identify exactly what's causing poor scores.
Use Google PageSpeed Insights. Visit pagespeed.web.dev and enter your URL. The tool analyses your page and provides specific recommendations. Pay attention to:
- Overall scores for mobile and desktop
- Specific LCP and CLS measurements
- Opportunities section listing improvements
- Diagnostics showing what's slowing your site
Check Google Search Console. Navigate to the Core Web Vitals report. This shows which pages have poor, need improvement, or good ratings. It identifies patterns across your entire site rather than individual pages.
Test real user data. PageSpeed Insights shows both lab data (simulated tests) and field data (real user experiences). Field data matters more because it reflects actual visitor experiences.
Run tests on multiple pages, not just your homepage. Product pages, blog posts, and landing pages might have different issues requiring different solutions.
Fixing LCP: Make Your Largest Content Load Faster
LCP measures when your largest visible content element becomes viewable. This is typically a hero image, banner, or large block of text above the fold.
Identify Your LCP Element
PageSpeed Insights tells you which element causes your LCP. Look in the diagnostics section for "Largest Contentful Paint element." Common LCP elements include:
- Hero images at the top of pages
- Banner images or sliders
- Large heading blocks with background images
- Video thumbnails or embedded content
Once you know the element, optimise it specifically.
Optimise Images for LCP
Images are the most common LCP element. Several optimisation techniques dramatically improve loading times.
Compress images before uploading. Use tools like TinyPNG, ShortPixel, or ImageOptim to reduce file sizes by 50–80% without visible quality loss. A 2MB image compressed to 200KB loads 10 times faster.
Use modern image formats. WebP images are 25–35% smaller than JPEGs at the same quality. AVIF offers even better compression. Modern browsers support these formats, with automatic fallbacks for older browsers.
Resize images to actual display size. Don't upload 3000px wide images if they display at 800px. Resize images to match their largest display dimensions. Save separate sizes for mobile and desktop if needed.
Implement lazy loading correctly. Lazy loading delays image loading until users scroll near them. This helps overall performance but can affect LCP. Never lazy load your LCP image. Add loading="eager" to ensure it loads immediately.
Preload your LCP image. Add a preload link in your page header:
This tells browsers to prioritise loading that specific image before other resources.
Reduce Render-Blocking Resources
CSS and JavaScript files often block page rendering, delaying LCP. Optimise these resources to speed up initial page display.
Minimise CSS file sizes. Remove unused CSS rules. Many sites load entire framework files when they only use a small portion. Tools like PurgeCSS automatically remove unused styles.
Inline critical CSS. Extract the CSS needed for above-the-fold content and include it directly in your HTML head. This eliminates the need to download a separate CSS file before rendering visible content.
Defer non-critical CSS. Load styles for below-the-fold content after the initial page render. Use the media attribute or JavaScript to load these files asynchronously.
Minimise and compress JavaScript. Combine multiple script files into one. Minify to remove whitespace and comments. Enable GZIP or Brotli compression on your server.
Defer JavaScript execution. Add defer or async attributes to script tags. This prevents JavaScript from blocking page rendering while downloading:
Professional web design services implement these optimisations during development, ensuring fast loading from launch rather than requiring fixes later.
Improve Server Response Times
Slow servers delay everything, including LCP. Your Time to First Byte should be under 600ms.
Upgrade hosting if necessary. Shared hosting often struggles under traffic. Consider VPS or dedicated hosting for business sites. Australian servers serve Australian visitors faster.
Implement comprehensive caching. Configure browser caching, page caching, object caching, and CDN caching at multiple levels.
Use a Content Delivery Network. CDNs serve content from the nearest server, reducing response times significantly.
Optimise database queries and reduce redirects. Review slow queries, add indexes, and eliminate redirect chains that add round trips.
Fixing CLS: Eliminate Unexpected Layout Shifts
CLS measures how much visible content shifts position during page load. Every unexpected movement adds to your CLS score. Lower is better.
Identify Layout Shift Sources
PageSpeed Insights shows which elements cause layout shifts. Common culprits include:
- Images loading without defined dimensions
- Advertisements inserting dynamically
- Fonts changing during page load
- Popups or banners appearing unexpectedly
Watch your own site load slowly to see shifts yourself. Use browser throttling in Chrome DevTools to simulate slow connections.
Set Image and Video Dimensions
The most common CLS cause is images loading without reserved space. When images load, they push content below them downward.
Always specify width and height attributes:
Modern browsers use these dimensions to calculate aspect ratios and reserve space, even before images load.
Use aspect ratio boxes for responsive images. When images scale responsively, maintain aspect ratios with CSS:
.image-container {
aspect-ratio: 16 / 9;
}
This reserves the correct space regardless of screen size.
Reserve Space for Ads and Embeds
Advertisements and embedded content (like social media feeds) often cause major layout shifts.
Define minimum heights for ad slots. Even if ads load dynamically, reserve appropriate space:
.ad-container {
min-height: 250px;
}
Use placeholder elements. Insert placeholder boxes matching typical ad dimensions. When real ads load, they fill these spaces without shifting content.
Lazy load below-the-fold ads. Don't load advertisements until users scroll near them. This prevents shifts in initially visible content.
Handle Web Fonts Properly
Custom web fonts can cause text shifts when loading, replacing system fonts.
Use font-display: swap to display text immediately in fallback fonts:
@font-face {
font-family: 'CustomFont';
font-display: swap;
}
Preload critical fonts used in visible content and match fallback font metrics to minimise visible shifts. Consider using system fonts for body text to avoid loading delays entirely.
Avoid Inserting Content Above Existing Content
Never insert content above the fold after initial page load unless responding to user interaction.
Load critical content in initial HTML. Don't rely on JavaScript to insert important above-the-fold content. Include it in your original HTML.
Add content below existing elements. If you must insert dynamic content, add it at the end of sections rather than at the beginning.
Use transforms for animations. CSS transforms don't trigger layout shifts. Use transform: translateY() instead of changing top or margin properties.
Maintaining excellent user experience through comprehensive website maintenance ensures your site stays optimised as you add new features and content.
Advanced Optimisation Techniques
Once you've addressed basic issues, these techniques provide additional improvements.
Implement resource hints. Use DNS prefetch, preconnect, and prefetch to prepare browsers for upcoming network requests:
Optimise CSS delivery. Extract above-the-fold CSS and inline it. Load remaining styles asynchronously. Use CSS containment to isolate component rendering.
Reduce third-party impact. Audit all external scripts. Remove unused ones. Load necessary scripts asynchronously. Consider self-hosting critical resources.
Monitor continuously. Set up automated monitoring through Google Search Console or dedicated tools. Test before deploying changes. Create performance budgets for images, scripts, and total page weight.
Implementing robust SEO services ensures your technical optimisations support your broader search visibility strategy.
Common Mistakes to Avoid
Over-optimising at the expense of functionality. Don't sacrifice important features just to improve scores. Balance user experience with performance.
Ignoring mobile performance. Mobile scores matter more than desktop scores for most sites. Always test and optimise for mobile first.
Focusing only on homepage. Product pages, blog posts, and other templates often have different performance characteristics. Optimise all important page types.
Not testing with realistic conditions. Test with throttled connections and lower-powered devices. Your high-speed office connection doesn't represent typical user experiences.
Forgetting about ongoing maintenance. Core Web Vitals scores degrade over time as you add content and features. Schedule regular audits and optimisations.
Your Next Steps
Start improving your Core Web Vitals today:
This week: Run PageSpeed Insights on your five most important pages. Note specific LCP and CLS issues. Compress and optimise your largest images.
This fortnight: Add width and height attributes to all images. Implement browser caching. Preload your LCP images.
This month: Audit and optimise third-party scripts. Implement critical CSS inlining. Set up performance monitoring in Google Search Console.
Ongoing: Test new pages before publishing. Monitor Core Web Vitals weekly. Address issues as they appear rather than letting them accumulate.
Fixing Core Web Vitals improves more than just rankings. Faster, more stable pages keep visitors engaged, increase conversions, and build trust in your brand. Start with the biggest issues identified in PageSpeed Insights, implement fixes systematically, and measure results. Your users and your bottom line will thank you.