Technical SEO → Site Speed
Site Speed:
Slow Pages Lose Rankings and Customers.
Page speed is a confirmed Google ranking signal — and every second of delay costs you both positions and conversions. The fixes are almost always the same six issues, in the same order of impact.
The Benchmark
What a Good Score Actually Looks Like
Google's PageSpeed Insights scores pages from 0–100. The score is a lab test — useful for diagnosis, but Google ranks based on real user field data from Core Web Vitals. Aim for 70+ on mobile and 85+ on desktop. Below 50 on mobile is a significant ranking liability.
Bounce Probability by Load Time (Google Research)
Checklist
- PageSpeed Insights mobile score above 70
- Images in WebP format and compressed
- Lazy loading on images below the fold
- Render-blocking JS deferred or async
- Browser caching configured
- TTFB under 600ms
- CSS and JS minified
- Third-party scripts loaded asynchronously
The Problems
The Six Speed Killers — Ranked by Impact
These six issues cause the vast majority of slow load times on small business websites. Fix them in order — the top three alone account for most of the performance gap.
| # | Issue | Impact | Fix | Typical Saving |
|---|---|---|---|---|
| 1 | Unoptimized Images | Very High | Convert to WebP, compress under 100KB per image, add lazy loading below the fold. | Up to 60% faster |
| 2 | Render-Blocking JavaScript | High | Add defer or async to non-critical scripts. Move third-party scripts to load after interaction. | 0.5–2s faster |
| 3 | Slow Server (High TTFB) | High | Upgrade hosting, add a CDN, or enable server-side caching. Target TTFB under 600ms. | 1–3s faster |
| 4 | No Browser Caching | Medium | Set cache-control headers for static assets. Repeat visitors load pages from cache instantly. | Repeat visits 2x faster |
| 5 | Unminified CSS & JS | Medium | Minify CSS and JavaScript files to remove whitespace and comments. Most build tools handle this automatically. | 5–15% faster |
| 6 | Too Many HTTP Requests | Low–Medium | Combine CSS files, use SVG sprites instead of image icons, and eliminate unused plugins. | Varies by site |
The Process
How To Diagnose and Fix a Slow Site
Start with measurement — you can't fix what you haven't diagnosed. Then work through the issues in impact order.
Run PageSpeed Insights on Mobile
Go to pagespeed.web.dev and test your most important pages on mobile. Mobile scores are what matter for rankings. The Opportunities and Diagnostics sections tell you exactly what to fix and by how much.
Fix Images First
Images are almost always the single biggest contributor to slow load times. Convert to WebP, compress each image, set lazy loading on anything below the fold, and add explicit width and height attributes to prevent layout shift.
Check Your TTFB
Time to First Byte measures server response time. If it's above 600ms, no front-end optimization will produce a fast page. Check TTFB in PageSpeed Insights under 'Server response times.' Fix with better hosting, a CDN, or server-side caching.
Defer Non-Critical Scripts
Every script that loads synchronously in the page head delays rendering. Add defer to non-critical scripts and async to independent ones. Third-party chat widgets and analytics can often be loaded after the first user interaction.
Validate in Google Search Console
After making fixes, check the Core Web Vitals report in GSC. Field data updates on a 28-day rolling window. This is the data Google uses for rankings — it's the final measure of success.
Find Out What's Slowing Your Site Down
A free technical SEO audit identifies your biggest speed killers and gives you a prioritized fix list — starting with the changes that will move your PageSpeed score the most.
Get My Free AuditFAQ
Common Questions About Site Speed
Does site speed affect SEO?
Yes — page speed is a confirmed Google ranking factor. Google introduced speed as a ranking signal for desktop searches in 2010 and extended it to mobile searches in 2018. The Page Experience update in 2021 further elevated speed's role by making Core Web Vitals (which include LCP, a direct speed metric) an official ranking signal. Beyond rankings, speed directly impacts conversion rates: research consistently shows that a 1-second delay in load time can reduce conversions by 7% or more.
How to improve site speed in SEO?
The highest-impact improvements for most small business sites, in order of effort-to-impact: compress and convert images to WebP format (biggest single gain), enable browser caching, defer non-critical JavaScript, minify CSS and JS files, upgrade to faster hosting or add a CDN, and reduce server response time (TTFB). For WordPress sites, plugins like WP Rocket handle caching, minification, and lazy loading without touching code. For Next.js sites, the Image component with lazy loading and WebP conversion is built in.
What is the ideal site speed?
Google's PageSpeed Insights classifies scores of 90–100 as 'Good,' 50–89 as 'Needs Improvement,' and 0–49 as 'Poor.' For SEO purposes, aim for a mobile score above 70 and a desktop score above 85. For Core Web Vitals specifically, the targets are LCP under 2.5 seconds, INP under 200 milliseconds, and CLS under 0.1. These thresholds are measured at the 75th percentile of real user field data in Google Search Console.
What is the 3 second rule in web design?
The 3-second rule is an industry benchmark stating that a web page should load within 3 seconds before most users abandon it. Research from Google found that as page load time goes from 1 to 3 seconds, bounce probability increases by 32%. From 1 to 5 seconds, bounce probability jumps 90%. For mobile users on slower connections, the stakes are even higher. The 3-second benchmark is a practical conversion target — from a pure SEO standpoint, faster is always better, and passing Core Web Vitals thresholds is the measurable goal.
A Faster Site Ranks Higher and Converts Better.
Griffin Mott Consulting diagnoses and fixes site speed issues for small businesses in Kansas City. Start with a free audit.