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Core Web Vitals in 2026: What Still Matters

LCP, INP, CLS — plus the newer metrics that quietly moved the goalposts. A practical playbook for fast sites in 2026.

April 11, 202610 min readBy Kenji Watanabe
Core Web Vitals in 2026: What Still Matters

Core Web Vitals aren't going away — they're getting stricter. Here's the 2026 playbook.

LCP is still about images

Nine times out of ten, LCP is a hero image. Serve modern formats (AVIF/WebP), size images to viewport, and preload the LCP resource.

INP replaced FID for a reason

Users can feel jank. Break up long tasks, defer non-critical JS, and lean on React 19 features like the compiler and useTransition.

CLS is a design problem disguised as an engineering problem

Reserve space for images, embeds, and fonts. Font-display: optional or swap with matching metrics keeps layout stable.

The quiet new metric: TTFB

Edge everything you can. Even the fanciest frontend loses to slow origins.

Fast sites aren't magic. They're the accumulation of a hundred small decisions made in the right direction.

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