Scroll Performance Test — Scrolling is the most common sustained rendering work a browser does, which makes it a good stress-free probe of device smoothness. This test auto-scrolls a sample panel at a constant speed for eight seconds, timestamps every frame, and reports the average frame rate plus the percentage of "long frames" — frames that took noticeably longer than the median.
The test runs entirely in your browser. Frame timings are measured locally and never sent anywhere.
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What is scroll performance test?
Scrolling is the most common sustained rendering work a browser does, which makes it a good stress-free probe of device smoothness. This test auto-scrolls a sample panel at a constant speed for eight seconds, timestamps every frame, and reports the average frame rate plus the percentage of "long frames" — frames that took noticeably longer than the median.
A healthy device scrolls with a long-frame ratio near zero percent. A few percent is normal on busy systems; a double-digit ratio is what your eyes register as stutter, and it usually means background work, an overloaded page, or thermal throttling is stealing time from rendering.
Because the workload is identical every run, the test is repeatable: re-run it after closing background apps, clearing storage pressure, or letting a hot device cool down, and compare.
How to use it
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Keep the tab visible
Background tabs are frame-throttled, which would fake a bad score.
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Start the test
The panel scrolls by itself for eight seconds — no input needed.
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Read the jank ratio
Average FPS plus the percentage of long frames tell you how smooth the device is.
Examples
Score guide
Interpreting the long-frame ratio.
Result: Near 0%: smooth. 1-5%: mostly smooth with occasional stumbles. Above 10%: clearly noticeable stutter — check background load and thermals.
Frequently asked questions
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Last reviewed: 2026-09-18