---
title: "Page Speed — monitoring glossary"
description: "Page speed is a colloquial term covering the time a page takes to become visually complete and interactive. It is measured by composite metrics like Core Web…"
canonical: "https://lemwatch.com/glossary/page-speed"
source: "https://lemwatch.com"
---

# Page Speed

> Page speed is a colloquial term covering the time a page takes to become visually complete and interactive. It is measured by composite metrics like Core Web Vitals, Speed Index, and Time to Interactive.

**Also known as:** Page load speed, Site speed

## Definition

 There is no single 'page speed' number. Different metrics capture different aspects: TTFB (server speed), FCP (first paint), LCP (main content paint), TTI (time to interactive), TBT (total blocking time), and Speed Index (the average paint over time).

 Google's PageSpeed Insights surfaces all of these and aggregates them into a 0-100 score using Lighthouse.

## Why it matters

 Page speed correlates directly with bounce rate, conversion rate, and SEO ranking. Amazon famously measured a 1% revenue drop for every 100 ms of additional load time. Optimising page speed is one of the highest-ROI engineering investments available.

 See it in the product: [Performance monitoring](https://lemwatch.com/features).


## Related

- [Monitoring glossary](https://lemwatch.com/glossary)
- [Lighthouse](https://lemwatch.com/glossary/lighthouse)
- [Core Web Vitals](https://lemwatch.com/glossary/core-web-vitals)
- [TTFB](https://lemwatch.com/glossary/ttfb)
- [LCP](https://lemwatch.com/glossary/lcp)
- [CDN](https://lemwatch.com/glossary/cdn)
- [All monitoring checks](https://lemwatch.com/features)
- [RDAP (Registration Data Access Protocol)](https://lemwatch.com/glossary/rdap)