Web Design · 25 February 2026 · 8 min read
Core Web Vitals fixes that actually change your scores
Practical LCP, INP and CLS fixes ranked by impact per hour of work, based on the sites we rebuild — plus how to avoid chasing lab scores that field data ignores.
Quick answer
The highest-impact Core Web Vitals fixes are: preload and properly size the LCP image, remove render-blocking CSS and fonts, defer or remove third-party scripts, set explicit dimensions on all media, and break long JavaScript tasks. Field data from real users, not Lighthouse lab scores, is what Google uses.
LCP: usually one image and one stylesheet
In order of impact
- Serve the hero image in modern format at the exact rendered size
- Preload it and never lazy-load the above-the-fold image
- Inline critical CSS, defer the rest
- Self-host fonts with font-display: swap and preload the primary weight
- Cut TTFB with edge caching before optimising anything on the page
INP: your JavaScript is doing too much
Fixes
- Audit third-party tags — chat widgets and heatmaps are frequent offenders
- Split long tasks and yield to the main thread
- Debounce expensive handlers on scroll and input
- Hydrate interactive components only when visible
CLS: reserve the space
Fixes
- Width and height attributes on every image and video
- Reserved containers for ads, embeds and cookie banners
- Avoid injecting banners above existing content after load
- Preload fonts to prevent late swaps shifting text blocks
Measure the right thing
Field over lab
Chrome User Experience Report field data drives the Core Web Vitals assessment. A perfect Lighthouse score on your laptop means little if real users on 4G mid-range Android phones see a 4s LCP.
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