PERFORMANCE · SEO GLOSSARY

PageSpeed Score

Lighthouse's 0–100 lab score measuring page performance under synthetic conditions — useful for diagnosis but not the same as Google's field-data ranking signals.

Definition

PageSpeed score (sometimes called Lighthouse score) is a composite 0–100 score that Google's Lighthouse tool generates by loading a page in a controlled lab environment and measuring performance metrics: First Contentful Paint, Speed Index, Largest Contentful Paint, Total Blocking Time, and Cumulative Layout Shift. The score is a weighted average of these lab metrics. A score of 90+ is "Good", 50–89 is "Needs Improvement", and below 50 is "Poor" by Lighthouse's definitions.

Why it matters for SEO

PageSpeed scores are useful for diagnosing performance problems — Lighthouse tells you exactly what's causing a slow score (render-blocking scripts, unoptimized images, unused CSS). But they are not what Google uses for ranking. Google ranks pages based on Core Web Vitals field data from real Chrome users (CrUX), not lab scores. A page can have a 95 PageSpeed score in lab but poor CrUX field data (due to real-world CDN issues, server location, or real device performance) — and vice versa. Treat PageSpeed score as a diagnostic tool, not as a ranking metric.

How DeepSEOAnalysis checks this

The audit includes PageSpeed Insights lab data as supplementary context. The primary signals for scoring are CrUX field data (real user measurements). Lab scores help diagnose what to fix; field data tells you whether users are actually experiencing good performance. Both are shown in the report so you can see whether lab improvements are translating to real-world improvements.