What is PLS by scroll behavior
PLS by scroll behavior breaks down your Perceived Load Speed (PLS) by the scrollability and scrolled state of the page at the time of view. It helps you understand whether scrollable pages (and whether they’ve retained a scroll position) impact how fast the page feels to load.
The scroll status refers to the state of the page — not whether a user physically scrolled during their session, but rather whether the page was scrollable and whether a previous scroll position was preserved (such as in back-navigation scenarios).
Scroll behavior states:
Non-scrollable — Page content fits entirely in the viewport.
Scrollable, Non-scrolled — Page could scroll, but no previous scroll state was restored.
Scrollable, Scrolled — The page restored a scroll position from a previous session or back-forward navigation.
Healthy PLS by scroll behavior sample
Should you worry
Pages with "Non-scrollable" or "Scrollable, Non-scrolled" states generally load faster, especially for static or lightweight views. However, “Scrollable, Scrolled” states often involve restoring a visual position deeper in the page, which can delay visual completeness and impact perceived speed.
This lens is particularly helpful when diagnosing performance issues related to return visits or client-side transitions — cases where scroll restoration might delay rendering.
Unhealthy PLS by scroll behavior sample
Slower PLS times often cluster under "Scrollable, Scrolled" pages. These pages may:
Trigger delayed layout shifts while restoring scroll
Require additional DOM hydration or lazy-loading below the fold
Suffer from inefficient rendering when jumping to deep positions on load
Even though users expect scroll to be preserved, the experience can feel slower if visual completeness is not immediate.
Resolving unhealthy PLS by scroll behavior
Go-to action plan to resolve an unhealthy PLS by scroll behavior:
Ask Uxi to analyze your PLS by scroll behavior and suggest improvements.
Use Filters to isolate "Scrollable, Scrolled" pages with high PLS and check which page types or devices show the greatest delay.
Simulate LCP of the suspected lens to see if fixing it will resolve the PLS by scroll behavior. If yes, this is where the resolution focus should be.
Use an automated optimization tool like Navigation AI to improve your PLS by scroll behavior.
Once you’ve improved PLS, set an alert to be the first to know if it starts worsening again.
Try it yourself
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