Google PageSpeed Insights

Written by Cobus van der Westhuizen, reviewed by Wynand van der Westhuizen, fact-checked by Lenata Oosthuizen. Last reviewed July 2026. Editorial policy.

What Is Google PageSpeed Insights?

Google PageSpeed Insights (PSI) is a free tool from Google that analyses the loading performance of a web page on both mobile and desktop devices. It generates a score from 0 to 100 based on how well the page performs against a set of performance metrics, and it provides a prioritised list of specific recommendations for improvement. The tool is available at pagespeed.web.dev and runs on the same Lighthouse audit engine that powers Chrome DevTools.

The score is broken into four colour-coded bands: 0 to 49 is poor (red), 50 to 89 needs improvement (orange), and 90 to 100 is good (green). Google feeds real-world performance data from Chrome users into the report through the Chrome User Experience Report (CrUX), so the tool shows both lab data from a simulated test and field data from actual users visiting your site.

For South African websites, mobile performance is particularly critical. A large proportion of local web traffic arrives on mobile devices, often over 4G connections that are slower than fixed-line broadband. A page that scores 90 on desktop may still score poorly on mobile if images are not optimised or third-party scripts are blocking render.

Core Web Vitals Explained

PageSpeed Insights reports three Core Web Vitals that Google uses as ranking signals. Largest Contentful Paint (LCP) measures how long it takes for the main content to load and should be under 2.5 seconds. Cumulative Layout Shift (CLS) measures visual stability as the page loads and should be below 0.1. Interaction to Next Paint (INP) measures responsiveness to user input and should be under 200 milliseconds. Failing any of these thresholds means your page experience may be affecting your search rankings.

Improving your PageSpeed score typically involves compressing images and converting them to modern formats such as WebP, deferring non-critical JavaScript, preloading key resources, and using a fast hosting provider or content delivery network (CDN). Each recommendation in the report comes with an estimated time saving so you can prioritise the changes with the greatest impact.

What Google PageSpeed Insights is

Google PageSpeed Insights (PSI) is a free tool from Google that analyses the performance of a web page and reports how fast it loads, along with specific recommendations for improving its speed and user experience. You enter a page's URL and PSI evaluates it, returning a performance score and detailed diagnostics covering how the page performs, particularly against the Core Web Vitals, Google's key user-experience metrics measuring loading (Largest Contentful Paint), interactivity/responsiveness (now Interaction to Next Paint) and visual stability (Cumulative Layout Shift). PSI reports two kinds of data: lab data (a controlled test of the page in a simulated environment, useful for diagnosis and consistent comparison) and, where available, field data (real-world performance from actual Chrome users via the Chrome User Experience Report, which reflects how the page actually performs for real visitors). Crucially, PSI also lists specific opportunities and diagnostics, concrete issues slowing the page (such as render-blocking resources, unoptimised images, excessive JavaScript) with guidance on fixing them, so it is not just a score but an actionable diagnostic tool. It reports for both mobile and desktop. Understanding PageSpeed Insights matters because page speed affects both user experience and SEO (through Core Web Vitals), and PSI is the standard, free tool for measuring a page's speed, understanding its Core Web Vitals, and getting a prioritised list of what to improve, making it a go-to resource for diagnosing and improving website performance.

Using PageSpeed Insights effectively

Using PageSpeed Insights effectively means treating it as a diagnostic and improvement tool rather than fixating on the single score, and understanding what the score does and does not mean. The headline performance score (out of 100) is a useful summary, but it is derived from lab data and is a guide, not the whole picture, so the more meaningful things are the Core Web Vitals assessment (especially the field data from real users, where available, since that reflects actual experience) and the specific opportunities and diagnostics PSI lists. The real value is in those recommendations: PSI identifies concrete issues slowing the page, such as render-blocking resources, images that should be compressed or properly sized, excessive or unused JavaScript and CSS, missing text compression, and layout-shift causes, and prioritises them by potential impact, giving a clear, actionable list of what to fix. Working through these, guided by their estimated savings, is how the tool improves a site. It is important to interpret the score sensibly: chasing a perfect 100 is often unnecessary and subject to diminishing returns, whereas passing the Core Web Vitals thresholds (the field-data assessment) and fixing the high-impact issues delivers the real user-experience and SEO benefit. Testing both mobile and desktop matters, since mobile performance (often weaker, and important where many users are on phones and slower connections) is weighted heavily. For a South African business, PageSpeed Insights is the practical tool to check a page's speed and Core Web Vitals, understand where it stands (ideally using real-user field data), and get a prioritised list of what to improve, then to work through the high-impact recommendations, rather than obsessing over the exact score. Because it directly surfaces the issues affecting speed and the Core Web Vitals that influence rankings, using PSI to diagnose and guide performance improvements is a sound, accessible part of technical SEO and user-experience work.

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