What polling rate measures
Polling rate is the frequency at which a mouse sends a position report to the computer, measured in hertz. A 1000 Hz mouse sends one report every millisecond. A 4000 Hz gaming mouse sends one every 0.25 ms, and an 8000 Hz gaming mouse every 0.125 ms.
It is not the same as sensor speed. The sensor may sample thousands of times per second regardless; polling rate governs how often those samples reach the operating system and, from there, your game.
The real latency difference
Going from 1000 Hz to 4000 Hz removes up to 0.75 ms of worst-case reporting delay; 8000 Hz removes about 0.875 ms. In isolation those numbers look trivial next to display and network latency.
What players actually notice is consistency. Denser reports mean the cursor path is described in finer steps, so fast flicks and tight micro-adjustments land where the hand intended instead of being interpolated between coarse samples. On a 240 Hz or 360 Hz monitor, several mouse reports arrive per frame and the motion reads as smoother.
What high polling rate costs
Every report is a USB transaction the CPU must service. On older or heavily loaded systems, 8K polling can measurably raise CPU usage and, in bad cases, cause frame-time spikes that undo the latency benefit.
On a wireless gaming mouse, higher polling rates also drain the battery faster, since the radio transmits far more often. Many players run 4000 Hz for ranked sessions and 1000 Hz the rest of the time.
How to test your polling rate
Use a browser-based mouse rate checker or a desktop polling-rate utility, then move the mouse in continuous circles for several seconds. Look at the average, not the peak — a stable 3900–4000 Hz average is healthy for a 4K device.
If the average collapses under load, try a direct rear-panel USB port, avoid unpowered hubs and make sure the wireless dongle sits in line of sight on your desk rather than behind the tower.