Website speed isn't just about user experience—it's a confirmed Google ranking factor. Core Web Vitals measure real-world user experience, and poor scores can hurt your SEO and conversion rates. For businesses in Birmingham, Coventry, Leicester, and across the Midlands, optimising website speed is essential for competitive advantage.
At Prebo Digital, based in Rugby, Warwickshire, we've helped countless UK businesses achieve excellent Core Web Vitals scores. This guide shares our proven optimisation strategies.
Understanding Core Web Vitals
Core Web Vitals are Google's metrics for measuring user experience:
LCP - Largest Contentful Paint
Measures loading performance:
- Good: ≤2.5 seconds
- Needs Improvement: 2.5-4 seconds
- Poor: >4 seconds
INP - Interaction to Next Paint (replacing FID)
Measures interactivity and responsiveness:
- Good: ≤200 milliseconds
- Needs Improvement: 200-500 milliseconds
- Poor: >500 milliseconds
CLS - Cumulative Layout Shift
Measures visual stability:
- Good: ≤0.1
- Needs Improvement: 0.1-0.25
- Poor: >0.25
Why It Matters: Google uses Core Web Vitals as a ranking factor. Sites with good scores rank better and convert better—studies show a 1-second delay can reduce conversions by 7%.
Improving LCP (Loading Speed)
Image Optimisation
- Use modern formats: WebP, AVIF
- Implement lazy loading for below-fold images
- Serve appropriately sized images (srcset)
- Compress images without quality loss
- Use a CDN for image delivery
Server Response Time
- Use quality UK-based hosting
- Implement server-side caching
- Use a content delivery network (CDN)
- Optimise database queries
- Consider static site generation where possible
Render-Blocking Resources
- Inline critical CSS
- Defer non-critical CSS
- Use async/defer for JavaScript
- Remove unused CSS and JS
- Minimise third-party scripts
Improving INP (Interactivity)
JavaScript Optimisation
- Break up long tasks (>50ms)
- Use web workers for heavy processing
- Implement code splitting
- Reduce JavaScript bundle size
- Remove unused JavaScript
Event Handler Optimisation
- Debounce scroll and resize handlers
- Use passive event listeners
- Avoid forced synchronous layouts
- Minimise main thread work
Improving CLS (Visual Stability)
Image and Video Dimensions
- Always specify width and height attributes
- Use aspect-ratio CSS property
- Reserve space for ads and embeds
Font Loading
- Preload critical fonts
- Use font-display: swap or optional
- Consider system fonts for body text
- Host fonts locally when possible
Dynamic Content
- Reserve space for dynamically loaded content
- Avoid inserting content above existing content
- Use CSS transforms for animations
Testing and Monitoring Tools
Free Tools
- PageSpeed Insights: Google's official tool
- Lighthouse: Built into Chrome DevTools
- WebPageTest: Detailed waterfall analysis
- GTmetrix: Performance reports
- Search Console: Core Web Vitals report
Field Data vs Lab Data
- Field data: Real user measurements (CrUX data)
- Lab data: Simulated testing environment
- Google uses field data for ranking
- Use lab data for debugging
Quick Wins Checklist
- ☐ Compress and optimise all images
- ☐ Enable browser caching
- ☐ Enable GZIP/Brotli compression
- ☐ Add width/height to all images
- ☐ Preload critical fonts
- ☐ Defer non-critical JavaScript
- ☐ Implement lazy loading
- ☐ Use a CDN
- ☐ Minimise redirect chains
- ☐ Remove unused plugins/code
Key Takeaways
- Core Web Vitals directly impact SEO rankings
- Focus on LCP, INP, and CLS metrics
- Optimise images—they're often the biggest culprit
- Minimise and defer JavaScript
- Always specify image dimensions
- Use real user data (field data) as your benchmark
- Monitor continuously—performance degrades over time
Need Website Speed Help?
At Prebo Digital, we're web performance specialists based in Rugby, Warwickshire. We help businesses across Birmingham, Coventry, Leicester, London, and the Midlands achieve excellent Core Web Vitals scores.
