Measure animation, then compare cadence
This page draws fifteen moving circles while recording requestAnimationFrame intervals. Current FPS is the rate over the last thirty intervals. Average FPS is the number of measured intervals divided by their total duration. Minimum and maximum are the reciprocal of the longest and shortest individual intervals, so one scheduling outlier can change either extreme.
The refresh-rate estimate uses a longer, lighter sampling loop to observe browser/display cadence. Both tools use the browser's animation clock, so their results often look similar. This workload is too small to predict gaming performance or certify GPU health.
Interpret a slower interval before blaming hardware
A six-second run can expose uneven pacing but cannot locate its cause. Browser scheduling, other tabs, power settings, screen mode and workload all affect the result. A 30 FPS result can reflect a browser cap or power policy; it does not establish a failing display.
- Run once with the tab visible and the browser window on the display you intend to test.
- Close unrelated heavy work and repeat under the same settings. Change one condition at a time.
- Compare average interval and worst interval, not only the best instantaneous FPS. Repeated large pauses warrant investigation of browser or system activity.
Hidden or unfocused runs are discarded rather than counted as poor performance. Timer precision and display synchronization limit accuracy. Results are local timing samples, with an optional saved summary and your visual assessment. For actual display defects, use the solid-color inspection.