What is TTFB by LCP
TTFB by LCP tracks how Time to First Byte (TTFB) - the earliest server-side metric, relates to Largest Contentful Paint (LCP) - a key visual load milestone.
TTFB marks when the server first responds. LCP marks when the main visible content renders. By comparing them, you’ll see how much of your load time is backend-driven vs frontend-rendering — and whether a slow start is dragging down the whole experience.
Healthy TTFB by LCP sample
Should you worry
In a healthy TTFB by LCP chart:
Fast TTFB values line up with fast LCP results.
There’s little gap between server response and visual rendering.
The whole chain — from request to visual content — is streamlined.
This usually means: fast edge/CDN delivery, smart HTML prioritization, and a lean render path on the frontend. Ideal!
Unhealthy TTFB by LCP sample
Issues appear when:
Slow TTFB, slow LCP: The server or origin is lagging, and that delay snowballs into late rendering. Often seen with unoptimized backends, dynamic pages, or cache misses.
Fast TTFB, slow LCP: The server responds quickly, but the frontend is bogged down. Could be due to render-blocking JS, heavy CSS, or late-loading hero content.
Slow TTFB, fast LCP: This can happen with aggressive caching or lazy-loading strategies — but it’s risky. Users might be shielded from backend lag, but not forever.
This lens helps you pinpoint where the loading chain breaks — at the server, in the network, or in the browser.
Resolving unhealthy TTFB by LCP
Go-to action plan to resolve an unhealthy TTFB by LCP:
Ask Uxi to analyze your TTFB by LCP values and suggest improvements.
Use Filters to explore which pages or regions are affected — maybe TTFB spikes in certain geos or device types.
Simulate TTFB of the suspected lens to see if fixing it will resolve the TTFB by LCP. If yes, this is where the resolution focus should be.
Use an automated optimization tool like Navigation AI to improve your TTFB by LCP values.
Once you’ve improved TTFB, set an alert to be the first to know if it starts worsening again.
Try it yourself
Discover how your website performs with real user data.