Tell me how your site feels. I'll tell you where to look.

A diagnostic guide to the three Core Web Vitals. Thresholds below are Google's published targets.

LCP
No symptoms
Largest Contentful Paint
How quickly the main content appears.
Good ≤ 2.5 s · Poor > 4 s
INP
No symptoms
Interaction to Next Paint
How quickly the page responds to input.
Good ≤ 200 ms · Poor > 500 ms
CLS
No symptoms
Cumulative Layout Shift
How much the layout jumps while loading.
Good ≤ 0.1 · Poor > 0.25

What are you noticing?

The main image or headline appears lateLCPText flashes or shifts when fonts loadCLSButtons feel slow or laggy to tapINPContent jumps as images or ads loadCLSChat widgets, tags and trackers pile upINPThe first byte takes a long timeLCP

Where to start

Select the symptoms you see and recommendations will appear here.

Vitals Lab is a fictional brand. This is a concept build by Hassnain Khan to demonstrate website performance optimization — not a real business or client project.