Insights · Checklist
Core Web Vitals triage checklist
Failing Vitals usually have a handful of causes: oversized images, render-blocking resources, slow fonts, heavy third-party scripts and elements that shift. This checklist finds them in order of likely impact and ends with a budget so they do not return.
How to use it
Before the first step.
- Start from field data in Search Console; lab tools confirm causes.
- Measure on real pages, on mobile, not on a test page.
Steps
Each one owned and evidenced.
| # | Step | Owner | Evidence |
|---|---|---|---|
| 01 | Pull field data by page group from Search Console and identify which metric fails where. | Technical owner | Field data export |
| 02 | Run lab measurement on representative failing pages at mobile settings. | Technical owner | Lab reports |
| 03 | For LCP: identify the largest element and its load path; fix image size, format, priority and server response. | Technical owner | Before and after LCP values |
| 04 | For LCP: remove or defer render-blocking stylesheets and scripts; inline only what the first screen needs. | Technical owner | Resource waterfall before and after |
| 05 | For INP: inventory scripts and tags; measure main-thread time per script; remove unjustified tags. | Technical owner with marketing | Tag inventory with decisions |
| 06 | For INP: defer non-essential script execution and break up long tasks. | Technical owner | Long task report before and after |
| 07 | For CLS: declare dimensions on every image and embed; reserve space for late-loading elements. | Technical owner | Layout shift report |
| 08 | For CLS: load fonts with a predictable strategy and avoid injecting content above the fold. | Technical owner | Font loading configuration |
| 09 | Confirm edge caching and compression for every static asset. | Technical owner | Response header capture |
| 10 | Re-measure field and lab; confirm all three metrics in the green at the 75th percentile on mobile. | Technical owner | Post-fix reports |
| 11 | Set a performance budget per page type and add a build check that fails pages exceeding it. | Technical owner | Budget file and failing test demonstration |
By David Selakovic · Published 2026-10-16 · Revised 2026-10-16 · Reviewed every 180 days