Mouse Input Lag Test: Measure Latency in Your Browser

Mouse Input Lag Test: Measure Latency in Your Browser

In a browser measurement, mouse input lag is the time between a physical action, whether moving or clicking, and the operating system registering that action. It includes USB controller scheduling, OS input stack processing, and PointerEvent delivery time. This tool measures all of these combined by recording PointerEvent timestamps and comparing consecutive event intervals.¹

The test captures both movement polling rate (Hz) and click latency (ms from press to event). Move your mouse inside the tracking zone to see the Hz chart. Click within the zone to log individual click-to-event latency values for each button press.²

What input lag includes in a browser measurement

Input lag in this context is not a single number from one source. It is a stack. At the hardware level, the mouse firmware queues reports at the configured polling rate. The USB controller schedules those reports across its polling window, with the polling interval determined by endpoint configuration and USB speed.³ The OS input stack processes the reports, applies any acceleration or smoothing filters, and queues them for application delivery; Windows pointer acceleration is also called ballistics and is applied to standard mouse movement data.⁴ Finally, the browser receives PointerEvents and calls your event listener. Each stage adds a fixed or variable delay. The total you see in this test is the sum of all stages, not the raw hardware response time.

Where latency spikes usually come from

At the application level, this tool records a timestamp with each PointerEvent and computes the interval since the previous one. Because all upstream stages complete before the event arrives, the measurement captures the full pipeline end to end rather than any single component in isolation. Dedicated hardware latency testers measure only switch actuation and produce lower absolute numbers; the gap between hardware testers and this tool represents the USB, OS, and browser overhead that exists in every real usage scenario.

Why browser results include more than the mouse

A browser test cannot bypass the OS input stack, so it measures what your setup actually delivers to the page. That makes the number more relevant for browser-based use, even though it will be higher than a bench tester reading. Use it to compare configurations on the same machine rather than to compare absolute numbers across different tools. The extra milliseconds captured in this test are not measurement error; they represent the real USB scheduling, OS input processing, and browser event delivery overhead that every click and movement actually passes through before reaching your game or application.

Running the same measurement before and after a single change is the disciplined way to use this tool. If disabling mouse acceleration drops your click log by 1 ms, you have proved the cause rather than assumed it. Stacking several changes at once hides which one mattered and makes the result hard to repeat. Treat each run as one variable so the next person can follow your exact steps.

Polling rate vs click latency: two measurements, two purposes

This tool shows two types of measurements. The Hz chart measures movement polling rate: how frequently the mouse reports position changes per second.³ The click latency log measures button response: the time from a physical button press to the browser receiving a mousedown event. These are related but distinct. A high polling rate reduces movement latency. Fast switch registration reduces click latency. A mouse can have excellent movement polling and slow click response, or low polling rate and fast click response. Checking both gives a complete picture of input responsiveness.

Reading both measurements at the same time

The two views run simultaneously. Move your mouse continuously while clicking at intervals inside the tracking zone: the Hz chart updates from movement events and the click log updates from button events. Running both together shows whether high polling rate coexists with low click latency, or whether USB contention hurting Hz also elevates click latency.⁵ A mouse with excellent polling rate but consistently elevated click latency usually has a debounce setting that can be reduced in companion software.

Reducing input lag in practice

Four changes produce the largest reductions in measured input lag. Connect your mouse to a direct rear motherboard USB-A port to reduce hub scheduling contention. Disable USB selective suspend in Windows Device Manager, since USB power management can pause an idle device and delay reports until it resumes.⁶ Increase your mouse's polling rate setting to its maximum in companion software. Finally, disable mouse acceleration ("enhanced pointer precision" on Windows) if you want pointer movement to avoid Windows ballistics.⁴

Because each of the four steps targets a different pipeline stage, applying them in sequence rather than all at once helps identify which stage was responsible for the improvement. If moving to a rear USB-A port resolves your latency, hub scheduling was the cause. If disabling USB selective suspend fixes the polling rate but click latency stays elevated, the debounce setting needs attention. Working through the steps in order gives you a clear baseline and avoids attributing an improvement to the wrong source.

When to use this

Use this test when diagnosing sluggish or inconsistent mouse response, when comparing two mice side by side, or when checking how mouse input lag is measured after a hardware change like a new cable, port, or firmware update.

Examples