Frame Rate Test

In short Frames per second is only half the story, and this shows the other half: how evenly those frames are spaced. A display running a steady 60 fps looks smoother than one averaging 90 with irregular gaps, because the eye notices the variation rather than the average. That is why a result that reads fine and still feels stuttery is not a contradiction — look at the consistency figure rather than the number. In a browser the usual causes of uneven frame times are an extension doing work on every frame, a background tab running something heavy, hardware acceleration being off, or a page with expensive CSS effects. Testing in a private window with extensions disabled separates the browser from the page in about thirty seconds. One thing this cannot tell you: it measures what the browser achieves, not what a game achieves. A browser is subject to throttling and compositing that a full-screen application is not, so a poor reading here does not necessarily predict game performance, and a good one does not guarantee it.