Addy Osmani Core Web Vitals Audit

Follow Addy Osmani's Core Web Vitals audit framework to evaluate field metrics, profile main thread execution, and resolve site performance bottlenecks.

5 time blocks, 30 minutes in total.

Time blocks

Field Data Baseline Review: 5 min
Review CrUX field data for 75th percentile LCP, INP, and CLS
Lab Performance Trace: 10 min
Record CPU and network throttled traces in Chrome DevTools
LCP and Resource Audit: 5 min
Isolate the hero element and analyze render delay bottlenecks
Interaction and Long Task Profiling: 5 min
Find long tasks over 50ms blocking main thread responsiveness
Layout Stability Inspection: 5 min
Locate unsized images or web font swaps causing page movement

About this routine

Addy Osmani, Engineering Lead at Google Chrome, advocates for performance auditing focused on real user experience. Addy Osmani's Core Web Vitals audit centers on three core user metrics: Largest Contentful Paint for loading speed, Interaction to Next Paint for responsiveness, and Cumulative Layout Shift for visual stability.

The audit starts by comparing real field data from the Chrome User Experience Report against lab traces captured in Chrome DevTools. By profiling CPU usage and main thread tasks under throttled conditions, engineers can pinpoint exactly where delays occur during page load and user interaction.

Applying this structured sequence helps web teams isolate long tasks, remove render blocking scripts, and stabilize dynamic elements. Performing this review regularly ensures web applications remain fast and responsive across diverse devices and network environments.

Why this routine works

Pinpoints actual loading and responsiveness issues experienced by real users
Isolates long JavaScript tasks that cause interface delays
Prevents sudden page movement by identifying layout shift sources
Establishes actionable performance priorities for web engineering teams

FAQ

What is Addy Osmani's Core Web Vitals audit?

It is a systematic performance review created by Google Chrome engineering manager Addy Osmani to diagnose site speed, loading speeds, responsiveness, and visual layout stability using field data and DevTools lab traces.

How long does a Core Web Vitals audit take?

A standard diagnostic review takes 30 minutes, covering field metric inspection, lab trace analysis, interaction profiling, and layout shift troubleshooting.

Which tools are used in this performance audit?

The audit uses PageSpeed Insights, Chrome User Experience Report data, and Chrome DevTools Performance panel.

Sources

Optimizing Core Web Vitals, Addy Osmani
Core Web Vitals Audit Workflow, web.dev