"The site feels slow" is one of the least useful sentences in software. Performance work only gets done when you replace feelings with numbers — and then watch those numbers over time.
The metrics that actually matter
Google’s Core Web Vitals give you a shared language: Largest Contentful Paint for loading, Interaction to Next Paint for responsiveness, and Cumulative Layout Shift for visual stability. These map closely to how a real person experiences your page.
Lab data vs field data
Lab tools like Lighthouse give you a controlled, repeatable score. Field data from real users tells you what is actually happening on the messy devices and networks your customers use. You need both — one to diagnose, one to prioritise.
A practical monitoring toolchain
- Lighthouse & PageSpeed Insights for lab audits
- Real-user monitoring for field vitals
- Budgets in CI so regressions fail the build
- Alerting when a key vital crosses a threshold
Performance is a feature, and like any feature it needs owners and a feedback loop. We help teams put that loop in place so speed stops being an afterthought.