Google PageSpeed Insights measures technical performance — load speed, Core Web Vitals, accessibility, and SEO metadata. roast.page includes PageSpeed data and adds AI vision analysis, copy evaluation, trust signal assessment, and conversion strategy scoring across 8 weighted dimensions. A page scoring 95/100 on PageSpeed can still convert at 0.5% because speed is necessary but not sufficient — technical performance accounts for only 7% of conversion outcomes (roast.page, 1,000+ pages). The other 93% is messaging, trust, design, and CTA effectiveness.
What does Google PageSpeed Insights do well?
PageSpeed runs Google's Lighthouse engine and returns detailed technical diagnostics. Google uses these exact metrics for search ranking — making PageSpeed authoritative and irreplaceable for technical optimization. If your LCP is 4.2 seconds, PageSpeed identifies exactly which resource is blocking it. Google's research confirms each additional second of load time increases bounce probability by 32%. For page speed optimization, PageSpeed Insights is the source of truth. It's free and processes 25,000 analyses per day.
What can't PageSpeed Insights tell you?
PageSpeed has no opinion on whether your headline communicates value. It doesn't know your CTA is buried below three paragraphs of features. It can't evaluate whether your trust signals match your buyer's expectations. It doesn't see the page the way visitors do. The median page scores 5.7/10 on Technical & SEO (the highest dimension median) but only 4.8/10 on Copy & Messaging and 4.2/10 on Trust — the dimensions PageSpeed cannot measure. 62% of SaaS pages lead with features instead of outcomes. 38% have zero testimonials. These conversion killers are invisible to PageSpeed.
How does roast.page use PageSpeed data?
Every roast.page analysis pulls real data from the Google PageSpeed Insights API (v5) — the same Lighthouse engine. Your performance metrics — LCP, CLS, FCP, INP, performance score, accessibility, SEO, and best practices — appear in the Technical & SEO dimension (7% weight). The AI references specific metrics against Google's thresholds: "Your LCP is 4.2s — Poor by Google's standards." You get PageSpeed data plus conversion analysis in one report. Pages with LCP under 2.5 seconds score 12 points higher on average — not just on Technical & SEO, but across all dimensions, because slow pages get abandoned before visitors see the content.