Scroll Smoothness Tester
Scroll the makimono below to take a reading.
How it works
仕組みSmooth scrolling depends on your browser painting a new frame every time the display refreshes, whether that's 60, 120, or 144 times a second. When a frame takes too long, the picture visibly hitches. This tester watches frame timing while you scroll the test area, estimates your display's refresh rate, counts dropped frames, and reports how your mouse wheel or trackpad delivers its scroll steps.
While you're actively scrolling, any frame that takes over 1.6× your display's typical frame time is counted as dropped. A healthy setup stays under a few percent; sustained double-digit drops mean the browser can't keep up.
Heavy pages, browser extensions, low battery power modes, background tabs, and GPU driver issues are the usual suspects. Try the same test in a private window with extensions off to isolate the cause.
Trackpads and free-spinning wheels send many small pixel-mode deltas, which feel smooth. Classic notched wheels send big line-mode steps, which feel clicky. Neither is wrong, but drivers that inflate the step size make any page feel jumpy.