Page speed has been a Google ranking signal since 2018. In 2026 it remains one of the few factors you can directly control and measure. This guide covers the metrics AISeen checks, what thresholds Google uses, and which optimizations deliver the most improvement per effort.
What AISeen Speed Score Measures
- Time to First Byte (TTFB) — Server response time. Target: under 200 ms. Issues: slow hosting, no CDN, unoptimized database queries.
- HTML size — Uncompressed document size. Large HTML often indicates server-side rendering issues or unneeded inline data.
- HTTP version — HTTP/2 and HTTP/3 enable multiplexed requests, significantly reducing load time on connection-heavy pages.
- Compression — Brotli or gzip compression should be enabled for all text assets. Uncompressed HTML/CSS/JS is one of the cheapest fixes.
- Cache headers — Static assets should have long-lived
Cache-Controlheaders. Missing cache headers force browsers to re-download assets on every visit. - Resource hints —
<link rel="preload">,preconnect, andprefetchdirectives reduce perceived load time by front-loading critical resources.
The Biggest Speed Killers
In our analysis of 50,000+ sites, three issues appear most frequently:
- Render-blocking scripts — JavaScript files loaded in
<head>withoutdeferorasyncblock HTML parsing. - Unoptimized images — PNG files where WebP or AVIF would reduce size by 30–70% with no visible quality loss.
- No CDN — Serving static assets from a single origin adds 100–500 ms of latency for global users.
Prioritizing Your Fixes
Not every fix is equal. Start with server-level changes (TTFB, compression, HTTP/2) because they affect every page simultaneously. Then move to image optimization and resource hints. JavaScript deferral often requires code changes and should be tackled last.