Time to First Byte under 800ms at 75th percentile

ISO-25010 time-behaviour starts the clock the moment a user's browser makes a request. TTFB above 800ms at the 75th percentile means a quarter of your users wait over a second before a single byte arrives — before any CSS, JavaScript, or content can render. Slow TTFB compounds every downstream metric: LCP, FCP, and INP all start later. For server-rendered applications without caching, every page hit cold-starts an origin server and may trigger database queries, turning user-perceived speed into a hostage of backend latency.

Reduce origin latency by caching rendered output at the edge. For Next.js, enable Incremental Static Regeneration on data-heavy routes:

// app/products/page.tsx
export const revalidate = 60  // regenerate at most once per 60 seconds

For fully static pages, force static generation:

export const dynamic = 'force-static'

Place a CDN (Vercel Edge Network, Cloudflare, or AWS CloudFront) in front of your origin so cached responses are served from the edge nearest the user. Also ensure frequently-queried database columns are indexed — uncached queries are a leading cause of TTFB spikes above 800ms.