Google Lighthouse is one of the most practical free tools available for website owners. It runs an automated audit of your site and produces a scored report across five categories in about 60 seconds. If you have never run a Lighthouse audit on your website, you are missing straightforward, actionable feedback that could meaningfully improve your site's performance and search rankings.
What Lighthouse Is
Lighthouse is an open-source automated auditing tool built into Google Chrome and available through Google's PageSpeed Insights. It simulates how your page loads under realistic conditions and checks it against a large set of best practices. The result is a set of scores from 0 to 100 with specific recommendations attached.
How to Run It
There are two easy ways to run Lighthouse.
The first is through Chrome DevTools. Open your website in Chrome, right-click anywhere on the page, and select Inspect. Click the Lighthouse tab (you may need to look under the arrow that reveals additional tabs). Select the categories you want to audit, choose Mobile or Desktop, and click Analyze Page Load. The report generates in under a minute.
The second is through Google PageSpeed Insights at pagespeed.web.dev. Paste your URL and click Analyze. PageSpeed Insights uses Lighthouse under the hood and also shows real-world data from Chrome users when available - a useful addition to the lab results.
The Five Audit Categories
Performance - Measures how fast your page loads, covering metrics like Largest Contentful Paint (LCP), First Input Delay (FID), and Cumulative Layout Shift (CLS). These three are Google's Core Web Vitals and directly affect your search rankings.
Accessibility - Checks whether your site can be used by people with disabilities. It looks for things like image alt text, sufficient colour contrast, proper heading structure, and keyboard navigation support.
Best Practices - A general health check covering things like HTTPS usage, browser errors, deprecated APIs, and security headers.
SEO - Checks for on-page SEO basics: meta descriptions, title tags, crawlability, mobile friendliness, and structured data. Note that this does not evaluate your content quality or backlinks - only technical on-page factors.
PWA (Progressive Web App) - Checks whether your site meets the criteria for a Progressive Web App. For most small business websites, this category is low priority.
Understanding the Performance Score
The performance score is a weighted average of your Core Web Vitals and a few additional metrics. A score above 90 is considered good, 50 to 89 needs improvement, and below 50 is poor.
It is important to understand that Lighthouse is a lab test, not a measurement of real user experience. It simulates a mid-range mobile device on a throttled connection. Your score will differ from what your actual visitors experience, and it will vary between runs even on the same page. Use the score as a directional guide, not an absolute measurement.
The Most Impactful Opportunities for WordPress Sites
Lighthouse labels specific suggestions as Opportunities (potential savings) and Diagnostics (other issues). Focus on Opportunities first.
Largest Contentful Paint (LCP) - Usually caused by a large unoptimized hero image or slow server response. Compressing and properly sizing your images often fixes this.
Render-blocking resources - JavaScript and CSS files that prevent the page from displaying. A caching plugin like WP Rocket or LiteSpeed Cache handles most of this automatically.
Unused CSS and JavaScript - Plugins load scripts on pages where they are not needed. Asset Cleanup Pro or perfmatters can remove unused scripts on a per-page basis.
Building an Action Plan
Do not try to fix everything at once. After your first audit, pick the two or three Opportunities with the largest estimated savings. Fix those, re-run the audit, and verify the improvement. Then move to the next set.
For most WordPress sites, the highest-impact moves are: install a caching plugin, compress and resize images using something like ShortPixel or Imagify, and reduce the number of active plugins. These three changes alone often push a site from the 40s into the 70s or 80s. From there, the gains become more incremental but still worthwhile.
