Page speed is a direct Google ranking factor, a Core Web Vitals component, and one of the strongest predictors of user engagement and conversion rates. Yet most site owners check their speed score once, note it is not great, and move on without addressing the specific issues causing slowness.

A speed audit changes this by identifying exactly what is slowing your pages down, prioritising fixes by impact, and giving you a clear action list to work through. The performance gains from a thorough speed audit are often dramatic — pages that took 8 seconds to load can frequently be brought under 2 seconds with targeted optimisations.

How to Run a Speed Audit

Start with our free page speed checker to get an immediate assessment of your most important pages. For a deeper analysis, Google's PageSpeed Insights (pagespeed.web.dev) provides both lab data from controlled tests and field data from real Chrome users — the field data is what Google actually uses for ranking purposes, so pay particular attention to this section.

Run both mobile and desktop tests. Mobile scores are almost always lower and are more important for SEO since Google uses mobile-first indexing as we covered in our guide to mobile SEO.

Understanding the Metrics

Speed audits produce many metrics, but focus on these Core Web Vitals as covered in our guide to improving Core Web Vitals:

Largest Contentful Paint (LCP) — how long until the main content loads. Target: under 2.5 seconds. The most impactful metric for perceived load speed.

Interaction to Next Paint (INP) — how quickly the page responds to user interaction. Target: under 200ms.

Cumulative Layout Shift (CLS) — how much content shifts while loading. Target: under 0.1. Affects user experience significantly.

Time to First Byte (TTFB) — how long before the server starts responding. Target: under 600ms. A slow TTFB indicates server or hosting issues that cannot be fixed by front-end optimisations alone.

The Most Common Speed Issues

Unoptimised images. The single most common cause of slow pages. Large, uncompressed images can add several seconds to load time. Convert to WebP format, compress before uploading, and serve correctly-sized images for each device as we covered in our guide to image SEO.

Render-blocking resources. JavaScript and CSS files that load in the page head before the content renders. Defer non-critical JavaScript, inline critical CSS, and eliminate unused code.

No caching. Without browser caching, every visit reloads every file from scratch. Implement proper cache headers to allow browsers to store static resources locally.

No compression. Serving uncompressed HTML, CSS, and JavaScript files wastes significant bandwidth. Enable Gzip or Brotli compression on your server — typically a one-line addition to your .htaccess file.

Too many third-party scripts. Analytics, chat widgets, advertising scripts, social sharing buttons — each adds network requests and JavaScript execution time. Audit your third-party scripts and remove any that are not delivering measurable value.

Slow hosting. If your TTFB is consistently above 1 second, the problem is your server, not your code. Shared hosting at a low tier often produces poor TTFB regardless of front-end optimisation. Upgrading hosting or adding a CDN is sometimes the only effective fix.

Prioritising Speed Fixes

Google's PageSpeed Insights prioritises its recommendations by estimated impact. Work through them in order — the fixes listed at the top deliver the most improvement per hour of work. Image optimisation and render-blocking resource removal typically appear at the top of most site's recommendation lists and deliver the largest gains.

After implementing fixes, verify the improvement with our page speed tool and check that Core Web Vitals field data has improved in Google Search Console's Page Experience report.

Summary

A speed audit identifies specific, fixable causes of slow page load times. Run it with our page speed checker and Google's PageSpeed Insights, focus on mobile scores, and prioritise fixes by impact. Image optimisation, render-blocking resource removal, caching, and compression deliver the most improvement for most sites and can reduce load times by several seconds.

Missed the previous article? Read: How to Find and Fix Duplicate Content Issues on Your Site