What is TTFB by cookie name
TTFB by cookie name shows how Time to First Byte (TTFB) varies based on the presence of a specific cookie in the user session. This lens lets you connect server responsiveness to user types like returning visitors, logged-in users, A/B test groups, and others identified by cookies.
Only cookies that were detected during the selected period are shown.
This view is especially useful for surfacing backend issues that only affect certain users — like slow auth checks, conditional redirects, or cookie-specific caching mismatches.
Healthy TTFB by cookie name sample
Should you worry
In a healthy setup, all major cookie groups — or at least your most important ones — show fast TTFB values. This means the server responds quickly for every segment, regardless of personalization, login state, or test variant.
If even your most complex user states are getting a fast initial response, performance isn’t being held back at the server level.
Unhealthy TTFB by cookie name sample
If some cookie groups have significantly worse TTFB, that usually points to backend performance problems tied to conditional logic or configuration errors.
Common root causes include:
Authenticated users triggering slower server-side logic.
Feature flags or test groups bypassing CDN or hitting origin servers unnecessarily.
Sessions with complex cookies leading to heavier processing or blocking queries.
Because these issues only show up for specific cookies, they can be hard to catch — unless you're measuring TTFB by cookie name.
Resolving unhealthy TTFB by cookie name
Go-to action plan to resolve an unhealthy TTFB by cookie name:
Ask Uxi to analyze your TTFB by cookie name values and suggest improvements.
Use Filters to focus on the slowest cookie groups, then review associated locations, routes, or caching layers.
Simulate TTFB of the suspected lens to see if fixing it will resolve the TTFB by cookie name. If yes, this is where the resolution focus should be.
Use an automated optimization tool like Navigation AI to improve your TTFB by cookie name 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.