What is TTFB by HTTP status code
TTFB by HTTP status code shows Time to First Byte (TTFB) differs based on the HTTP status code received during page load. Since TTFB is heavily server-dependent, this lens can be a red flag detector for caching issues, redirect chains, or server errors.
This lens is especially useful for identifying server-side inefficiencies linked to specific code paths, redirect rules, or degraded fallback logic.
Healthy TTFB by HTTP status code sample
Should you worry
In a healthy setup:
TTFB is lowest for
200 OKresponses — your primary content routesRedirects (
301,302) are minimal and efficient404and500pages are quick to respond and don’t add unnecessary backend delay
This pattern reflects a well-optimized server architecture with fast routing, proper cache handling, and lean error delivery.
Unhealthy TTFB by HTTP status code sample
An unhealthy lens often reveals:
Slow TTFB on
3xxresponses — indicating redirect chains or non-cacheable hopsDelays on
404or500responses caused by slow backend error rendering200pages with poor TTFB, suggesting backend bottlenecks or resource-heavy rendering even on the main routes
These problems often go unnoticed during typical testing but affect real-world user speed and perception.
Resolving unhealthy TTFB by HTTP status code
Go-to action plan to resolve an unhealthy TTFB by HTTP status code:
Ask Uxi to analyze your TTFB by HTTP status code values and suggest improvements.
Use Filters to isolate problematic status codes and find where the backend logic or response flow breaks down.
Simulate TTFB of the suspected lens to see if fixing it will resolve the TTFB by HTTP status code. If yes, this is where the resolution focus should be.
Use an automated optimization tool like Navigation AI to improve your TTFB by HTTP status code 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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