Every extra second of load time costs conversions — roughly 4.4% per second on e-commerce, and similar on lead-gen sites. Core Web Vitals turn that pain into three measurable numbers.
The three numbers
- LCP — main content visible in under 2.5 seconds.
- INP — interaction response in under 200 milliseconds.
- CLS — layout stays stable while loading.
The four fixes that matter
First, compress and resize hero images — one oversized banner is the usual LCP killer. Second, host fonts locally and preload the main one. Third, defer third-party scripts; chat widgets and tag managers are the typical INP culprits. Fourth, set explicit width and height on media to stop layout shifts.
What not to chase
A perfect 100 Lighthouse score is not the goal. Field data from real users (CrUX) is what Google uses — optimise until real-user numbers pass, then stop and spend the time on content.
On the sites we rebuild, these four fixes alone typically take LCP from 4–5 seconds to under 2.
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