What is TTFB breakdown
TTFB breakdown lens decomposes Time to First Byte (TTFB) into the key backend and network components that influence how fast your server begins responding.
TTFB is the very first step in the loading experience — and often a hidden bottleneck. This lens shows where server-side or network delays are affecting that first byte.
Healthy TTFB breakdown sample
Should you worry
A healthy TTFB breakdown often includes:
Component | Ideal Time | Notes |
Server processing time | ≤ 100 ms | Fast backend logic and DB response. |
DNS time | ≤ 50 ms | Quick DNS lookup, especially with good resolver caching. |
Redirect time | ≤ 50 ms | If used at all, keep minimal and quick. |
Download time | ≤ 100 ms | Time to start receiving response after server sends it. |
These numbers reflect modern infrastructure with edge caching, global CDNs, and minimal latency.
Unhealthy TTFB breakdown sample
In the example below, the Server processing time is 328ms — a major bottleneck pointing to heavy backend logic, authentication delays, or unoptimized database queries.
Download time is also high at 310 ms, suggesting a delay between when the server starts responding and when the browser begins receiving data. This could point to issues with network congestion, poor compression, or lack of edge delivery.
When backend and delivery layers underperform, users never even get a chance to start loading the page — which directly impacts bounce rates and Core Web Vitals.
Resolving unhealthy TTFB breakdown
Go-to action plan to resolve an unhealthy TTFB breakdown:
Ask Uxi to analyze your TTFB breakdown values and suggest improvements.
Use Filters to isolate slow server response zones by geography, platform, or user type.
Simulate TTFB of the suspected lens to see if fixing it will resolve the TTFB breakdown. If yes, this is where the resolution focus should be.
Use an automated optimization tool like Navigation AI to improve your TTFB breakdown values.
Once you’ve improved TTFB, set an alert to be the first to know if it starts worsening again.
Try it yourself
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