Just hit start and move your mouse around in the browser. The values will fluctuate based on your movement and browser limitations, but it should give you a good sense of what your mouse is polling at.
Average Rate: N/A Hz
Peak Rate: N/A Hz
What are mouse polling rates?
Polling rates is a measure of how often your mouse reports back to your computer with information. 1000Hz = 1000 reports a second on your mouse clicks and sensor location. Learn more: What’s the best mouse polling rate for gaming?