Core Web Vitals Monitoring Checklist for Agencies

Why Agencies Need a Systematic Approach If you run an agency managing 10, 25, or 50+ client sites, you can't afford ad-hoc performance monitoring. One missed regression can cost you a client. One undetected CLS issue can silently tank a client's rankings for weeks before anyone notices. This checklist gives you a repeatable system. Use it for onboarding new clients, for weekly monitoring routines, and as a quality assurance checkpoint before and after major deployments. For metric fundamentals, see What Are Core Web Vitals? ; for budget thresholds, see our performance budget and template resources. The Checklist Phase 1: Client Onboarding Run these checks when you first take on a new client's site. [ ] Baseline all key pages — Run PageSpeed Insights (mobile + desktop) on the homepage, top 5 landing pages, and any high-conversion pages (pricing, contact, checkout) [ ] Record baseline scores — Document current LCP, INP, CLS, FCP, TBT, and overall Performance Score for each page [ ] Check