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Core Web Vitals: LCP, INP and CLS

1 min read

Pro feature. Errors Tracking is part of Opti-Behavior Pro. Start the 6-month free trial to unlock it.

Core Web Vitals are Google’s measures of page experience. Opti-Behavior measures them on your real visitors, per page and device.

MetricMeasuresGoodNeeds improvementPoor
LCP – Largest Contentful PaintTime to show the main content< 2.5 s2.5–4 s> 4 s
INP – Interaction to Next PaintDelay between a tap/click and the screen reacting≤ 200 ms200–500 ms> 500 ms
CLS – Cumulative Layout ShiftHow much the layout jumps while loading< 0.10.1–0.25> 0.25

How to improve them #

MetricCommon fixes
LCPCompress the hero image, preload it, use a cache and a CDN, reduce render-blocking CSS
INPRemove heavy scripts, delay third-party widgets, avoid long tasks on click
CLSSet width and height on images and embeds, reserve space for banners and ads

INP needs real interactions: “No interaction captured” means no visitor clicked or tapped during the measurement.

Why lab tools and real visitors differ #

PageSpeed Insights tests one load from a data centre. Opti-Behavior measures your real visitors on their own phones and connections, so it shows problems that appear only on slow networks or older devices – and tells you which pages real visitors actually use.

Expected result #

You know which vital fails on which page and device.

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