“Core Web Vitals” sounds abstract, but it maps to something very real: how fast your site feels, how responsive it is, and whether it jumps around while loading. Those factors affect conversions and can influence SEO—especially when your content is similar to competitors.
What are Core Web Vitals?
- LCP (Largest Contentful Paint): when the main content appears.
- INP (Interaction to Next Paint): how quickly the page responds to user actions.
- CLS (Cumulative Layout Shift): how stable the layout is while loading.
LCP: load speed users feel
LCP is usually dominated by your hero banner image, large headings, or above-the-fold sections. Common causes of bad LCP include unoptimised images, missing caching, slow server response, and render-blocking CSS/JS.
- Compress and serve images as WebP/AVIF where possible.
- Use proper caching headers and page caching.
- Reduce TTFB by fixing hosting resources and backend bottlenecks.
INP: responsiveness
INP is about how quickly the site reacts when someone taps a menu, clicks a button, or starts typing. Heavy JavaScript, too many third-party scripts, and poorly optimised themes commonly cause sluggish interaction.
- Defer non-critical scripts and remove what you don’t need.
- Avoid loading multiple libraries that overlap (e.g., duplicate sliders/frameworks).
- Keep forms and navigation lightweight.
CLS: layout stability
CLS is what users experience as “the page moved” just as they tried to click. It’s often caused by missing image dimensions, lazy-loaded banners without reserved space, injected cookie banners, or fonts swapping in late.
- Always set width/height (or aspect ratio) for images and embeds.
- Reserve space for cookie banners and dynamic UI.
- Use font loading strategies that prevent late reflow.
How to audit properly
Don’t rely on a single lab test. You want both lab and real-user data:
- Google PageSpeed Insights for quick diagnostics.
- Chrome DevTools Lighthouse for repeatable lab testing.
- Search Console for real-user (“field”) CWV trends.
What to fix first (highest ROI)
- Hero images: correct sizing + compression + next-gen formats.
- Caching: page caching, browser caching, and asset caching.
- Third-party scripts: remove or defer anything non-essential.
- Fonts and layout: prevent CLS with reserved space and sensible font loading.
Want a performance plan you can actually implement?
Turbo Digital can run a Core Web Vitals audit and give you a prioritised fix list (fast wins first), then implement the changes without breaking your site.
Request a Core Web Vitals Audit