What is TTFB by UTM Source
TTFB by UTM Source shows the Time to First Byte (TTFB) value across different UTM sources (e.g., newsletter_may). This lens helps you identify which UTM sources are associated with slower initial server responses, potentially due to differences in landing pages, user geolocation, or caching behavior.
The list includes only UTM sources that generated traffic to your website during the selected period.
TTFB reflects how quickly a user’s browser starts receiving data after making a request. It’s a foundational metric that affects all other Core Web Vitals - especially LCP and INP - because if TTFB is slow, everything else is delayed.
Healthy TTFB by UTM Source sample
Should you worry
A healthy TTFB by UTM source lens looks all green. Some UTM sources may show slightly better performance than others, but as long as there’s no yellow or red, it’s considered healthy. The greener the UTM source, the faster users begin loading your site.
Unhealthy TTFB by UTM Source sample
In the example below, TTFB by UTM source shows that the newsletter_may campaign has noticeably slow server response times. Visitors from this source may experience frustrating delays even before the page starts rendering, hurting bounce and conversion rates.
Resolving unhealthy TTFB by UTM Source
Go-to action plan to resolve an unhealthy TTFB by UTM Source:
Ask Uxi to analyze your TTFB by UTM Source values and suggest improvements.
Use Filters to isolate the slow UTM source in TTFB by UTM source, then cross-check with TTFB by page, country, or device to detect patterns.
Simulate TTFB of the suspected lens to see if fixing it will resolve the TTFB by UTM Source. If yes, this is where the resolution focus should be.
Use an automated optimization tool like Navigation AI to improve your TTFB by UTM Source 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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