Metrics

Each metric is the median of the measured runs. Times are in ms.

zs.measure

Metric	What it is
frame.max	Longest gap between two frames
frame.slow	Frames longer than two display frames (> 33.4 ms)
frame.long	Long animation frames (> 50 ms). Chromium only
input.down / input.move / input.up	Worst time from a pointer event to the next frame, per phase of a gesture
input.key / input.wheel	Same for key presses and wheel steps
input.click	Same for a click with no pointerup before it, such as Enter on a button. After a pointerup, its time is in input.up
cpu.main	Time the main thread spent running. It leaves out other programs, so it holds still on a busy machine. Chromium only

A metric only shows when its event happened: a click has input.down and input.up, typing has input.key.

frame.max and input.* over 50 ms, the point where a delay is visible, show a warning. Only the limits decide pass or fail.

zs.cycles

What stays behind after the cycles, with garbage collected before every sample. Chromium only.

Metric	What it is
memory.heapMB	JS heap growth, in MB. Memory held by ArrayBuffers, canvases and the GPU isn't in it
memory.nodes	DOM node growth, detached nodes included
memory.listeners	Event listener growth