SEO finding
A lab metric or the page weight got worse than the earlier runs of the same page
SEO Warning Severity: Medium
Part of the audit Page speed and Core Web Vitals. Finding id: seo.labMetricRegression.
What it costs you
A slowdown that nobody notices stays until visitors do.
What to do
Find the change that came with it and undo or fix it.
What it checks
- Speed test results got worse
- Page got heavier
How to fix it
Find the change behind the slowdown
- Open the latest run and the last good run of [url] on [device] side by side.
- Compare the request lists: look for a new file, a larger file or a new host.
- Check what was released between the two runs (theme, plugin, tag manager, content).
- Undo or fix the cause, then run the lab test again.
How to check: Two lab runs in a row are within the usual range of the earlier runs.
Thresholds
| Name | Default | Meaning |
|---|---|---|
min_increase_pct | 25 | Starting value. Smallest rise over the average of the earlier runs, in percent, that is reported. |
min_earlier_runs | 2 | Starting value. Earlier runs of the same page and device needed before a rise counts. One run is mostly noise. |
min_lcp_rise_ms | 300 | Starting value. LCP must also rise by at least this many milliseconds. |
min_tbt_rise_ms | 100 | Starting value. Total Blocking Time must also rise by at least this many milliseconds. |
min_bytes_rise | 200000 | Starting value. Transfer size must also rise by at least this many bytes. |
How to verify by hand
A second lab run (reverify runs: 2). Lab values move from run to run, so one slow run alone proves little.
What this relies on
The average of earlier runs is what the page normally does, and the change is not a one-off slow run.