Page speed
What is page speed?
Page speed is how quickly a web page loads, shows its main content and becomes responsive to clicks and taps. It is not one number: a page can start drawing quickly but take seconds to show its main image, or look finished but freeze when someone taps a button.
Google measures speed for search through Core Web Vitals: Largest Contentful Paint for loading, Interaction to Next Paint for responsiveness and Cumulative Layout Shift for visual stability. Supporting metrics include time to first byte, First Contentful Paint and, in lab tests, Total Blocking Time.
There are two kinds of speed data. Field data comes from real visitors, such as the Chrome User Experience Report (CrUX) that Google uses. Lab data comes from a test run in a controlled environment, such as Lighthouse. Field data is what Google’s ranking systems look at; lab data is what you use to find and fix the causes.
Why page speed matters for SEO
Speed affects people first. Slow pages lose visitors before they see anything, and sluggish pages frustrate the ones who stay. That shows up in engagement and conversions whatever happens in search.
For SEO, Core Web Vitals are part of the page experience signals Google’s ranking systems use. Google is clear that relevance and helpful content come first and a fast page will not outrank a much more relevant one, but when results are otherwise close, a better experience can help. Very slow servers can also reduce how much Google crawls, since Googlebot slows down when a site responds slowly.
How to improve page speed
- Measure first. Check field data in PageSpeed Insights or the Core Web Vitals report in Search Console, then use Lighthouse to find causes.
- Speed up the server response with caching, faster hosting or a CDN.
- Compress and resize images, serve modern formats such as WebP or AVIF, and give the main image a high fetch priority.
- Cut and defer JavaScript: remove unused code and third-party scripts, and load non-critical scripts with defer or async.
- Remove render-blocking resources by inlining critical CSS and deferring the rest.
- Set width and height on images and reserve space for ads and embeds to avoid layout shifts.
- Lazy-load images and iframes below the fold, but never the main image at the top.
Page speed FAQ
Is page speed a ranking factor?
Yes, through Core Web Vitals and page experience, but a modest one. Google says it will still rank the most relevant, helpful page first even if it is slower.
What is a good page load time?
Rather than one load time, aim for Google’s Core Web Vitals thresholds at the 75th percentile of visits: LCP within 2.5 seconds, INP within 200 milliseconds and CLS of 0.1 or less.
Why do my PageSpeed Insights scores change every time?
The performance score comes from a single Lighthouse lab run, which varies with network, server load and third-party scripts. The field data section, based on 28 days of real visits, is more stable.
Related SEO terms
Core Web Vitals are Google’s three metrics for real-world page experience: Largest Contentful Paint, Interaction to Next Paint and Cumulative Layout Shift.
Largest Contentful Paint (LCP)
Largest Contentful Paint (LCP) is a Core Web Vital that measures when the largest image or text block in the viewport appears. Good is 2.5 seconds or less.
Interaction to Next Paint (INP)
Interaction to Next Paint (INP) is a Core Web Vital that measures how quickly a page responds to clicks, taps and key presses. Good is 200 ms or less.
Cumulative Layout Shift (CLS) is a Core Web Vital that measures how much content moves unexpectedly while a page is used. Good is 0.1 or less.
Time to First Byte (TTFB) is the time from requesting a page until the first byte of the response arrives. It sets the floor for every other speed metric.
PageSpeed Insights is Google’s free tool that shows a page’s real-user Core Web Vitals and a Lighthouse lab test with suggestions, for mobile and desktop.
Lighthouse is Google’s open-source tool that tests a page in a lab and scores its performance, accessibility, best practices and SEO.