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Slow first byte (TTFB)

performance.cwv_ttfb_slow
Priority
Low
Severity
Warning

What we look for

In Google's PageSpeed Insights test, the server took more than 0.8 seconds to start sending each of these pages, a measure called TTFB (Time to First Byte).

Why it matters

Everything else on the page waits for the first byte, so a slow start delays every other measure.

How to fix

Turn on page caching in your CMS or hosting, use a CDN (a network that serves your site from servers near each visitor), and ask your host about slow database queries or an underpowered server.

What it cannot know

Google measures from its own servers, so the time depends partly on how far they are from yours.

Where you’ll see it

The id is stable, and every surface uses it, so it’s the thing to search for or hand to an agent.

Terminal
When it is one of the five findings under Fix first, raptor crawl prints the id under it.
Check: performance.cwv_ttfb_slow
crawl.json and the CSV
The crawl JSON names the finding by this id, and so do the CSV and raptor_query.
"check_id": "performance.cwv_ttfb_slow"
The HTML report
This link opens the finding in the report, and each finding shows its id.
crawl.html#finding=performance.cwv_ttfb_slow
MCP
raptor_findings with this check_id returns the finding in full, with a fix brief ready to paste into a task. If it didn’t fire, it says why.
raptor_findings {
  "job_id": "...",
  "check_id": "performance.cwv_ttfb_slow"
}