A fast website matters as much as a good-looking one. Slow pages frustrate visitors, cost you enquiries and sales, and can hold back your search visibility. The good news: free tools show you exactly what is slowing your site, and most fixes don’t require giving up functionality. Test first, fix the biggest problem, then test again.
What Google Measures: Core Web Vitals
Google’s Core Web Vitals are three metrics that describe real-world page experience. A page passes when it meets the “good” threshold for at least 75% of visits (web.dev):
- Largest Contentful Paint (LCP): how fast the main content appears. Good is 2.5 seconds or less.
- Interaction to Next Paint (INP): how quickly the page responds when someone taps, clicks or types. Good is 200 milliseconds or less.
- Cumulative Layout Shift (CLS): how much the layout jumps around while loading. Good is 0.1 or less.
INP replaced First Input Delay (FID) as a Core Web Vital on March 12, 2024 (web.dev). Older guides that tell you to optimize FID are out of date. INP is stricter, because it looks at responsiveness across the whole visit, not only the first interaction.
Free Tools to Test Website Speed
Google PageSpeed Insights
Start with PageSpeed Insights. Enter a URL and it shows two kinds of data (Google):
- Field data from the Chrome User Experience Report (CrUX): how real Chrome users experienced the page over the previous 28 days. This is what your Core Web Vitals assessment is based on.
- Lab data from Lighthouse: a simulated test with a performance score and a list of specific problems to fix.
If a page has too little traffic for field data, you will only see lab results. Treat the lab score as a diagnostic, not a target in itself.
Google Search Console
The Core Web Vitals report in Google Search Console groups your URLs into good, needs improvement and poor, using the same field data. It is the quickest way to see which templates or sections of a large site need work.
Chrome DevTools and Lighthouse
Chrome’s built-in DevTools are free and powerful. The Performance panel shows your local LCP and CLS as soon as you open it, and INP once you interact with the page, and it can compare them with real-user field data (Chrome for Developers). The Lighthouse panel runs the same lab audit as PageSpeed Insights. Since Lighthouse 13, its performance recommendations are presented as “insights” that point to specific causes, such as layout shift culprits and costly third-party scripts (Chrome for Developers).
Other Speed Test Tools
- Pingdom Website Speed Test: a quick test from several locations, with a breakdown of every file the page loads.
- GTmetrix: a performance report with a waterfall chart and video playback of the page loading. Check its current plans, because test locations and limits depend on your account.
- WebPageTest: detailed tests on real browsers and connection speeds, useful when you need to see exactly what loads when.
Different tools use different locations, devices and connections, so their numbers won’t match. Pick one, use the same settings each time and compare against your own earlier results.
How to Fix a Slow Website
Optimize Images
Images are often the largest files on a page and a common cause of slow LCP. Resize them to the size they display at, compress them, and use modern formats: WebP and AVIF are supported by about 97% and 96% of browsers in use (Can I use). Lazy-load images below the fold, but not the main image at the top of the page. Always set width and height so the layout doesn’t jump, which helps CLS.
Use Caching
Caching stores ready-made copies of your pages and files so they don’t have to be rebuilt for every visitor. Many hosts provide server-level caching. If your site runs on WordPress, a caching plugin such as W3 Total Cache, which is still actively maintained, can be set up in minutes. Use one caching plugin, not several, and test your site after enabling it.
Set Up a Content Delivery Network
A content delivery network (CDN) serves your files from servers close to each visitor instead of from one location, so pages load faster for people in other cities and countries. Providers include Cloudflare, Amazon CloudFront, Fastly and CacheFly. If an older guide recommends MaxCDN, note that the service was retired at the end of 2022. Many CDNs also help protect your site against DDoS attacks and abusive bots, and support HTTP/3, a newer protocol that most browsers now handle.
Reduce and Compress JavaScript and CSS
Heavy JavaScript is the most common cause of poor INP, because the browser can’t respond to a tap while it is busy running scripts. Remove plugins and third-party tags you don’t need, load non-essential scripts later, and break up long tasks. Minify CSS and JavaScript to strip spaces and comments, and enable compression such as Brotli or gzip on your server. Many CMS platforms, caching plugins and build tools do this automatically.
Skip Outdated Tricks
Some advice from older guides no longer helps much. CSS sprites, which combined many small images into one file to save HTTP requests, matter far less on HTTP/2 and HTTP/3, which load many files at once. Popular sprite generators from that era are no longer maintained. Focus on image weight, JavaScript and server response time instead.
Keep Testing
Speed is not a one-time project. New plugins, tracking tags and campaign images slow sites down over time, so recheck your key pages every month and after every major change. Fast pages also help visibility in AI search, as we explain in our generative engine optimization checklist.
If you would rather hand this off, our GEO and page speed services team can audit and fix your Core Web Vitals. Or skip the plugin juggling: Apex®, the AI-native digital experience platform (DXP), includes caching and AWS hosting as part of the platform.
