Core Web Vitals & site speed: the ranking tie-breaker that moves conversion

Run PageSpeed Insights on two pages, read LCP/INP/CLS against Google's thresholds, fix the usual Shopify culprits — and let AI turn the report into a plain-language fix list.

Core Web Vitals are only a ranking tie-breaker, but speed is a proven conversion lever — Farfetch's data tied every 100ms of LCP to ~1.3% of conversion. Measure, fix the biggest culprits, and confirm in field data.

Google grades every page on three field metrics, measured at the 75th percentile of real visitors. The "good" thresholds (per Google's web.dev): LCP ≤ 2.5s (how fast the main content paints), INP ≤ 200ms (how fast the page responds to taps, INP replaced FID in March 2024), CLS ≤ 0.1 (nothing jumps around while loading).

Passing is only a ranking tie-breaker, worth a position or two between similar pages. But the conversion upside is real: Farfetch's published engineering data showed conversion dropping ~1.3% for every extra 100ms of LCP.

You read the report; AI turns it into a fix list you can actually follow.

What you'll learn

Measure two pages
Read the three scores
Fix the usual Shopify/theme culprits, in payoff order
Paste the report into the prompt above
Re-test, then wait for field data