Keyboard Input Lag: A Controlled Troubleshooting Guide
Keyboard input lag is a delay between an intended press and the response you notice. The delay can involve the keyboard, wireless link, operating system, application or display. Compare the same input in a local text editor and the affected app before changing hardware settings.
The key timing test exposes browser-observed timing. It cannot establish the moment the physical switch actuated, true USB polling rate or total press-to-pixel latency.
Describe the delay precisely
| Observation | Useful comparison |
|---|---|
| First press works, held repetition starts late | Operating-system repeat delay |
| Short taps are ignored but long presses work | Slow Keys or input-filter settings |
| Several characters appear in a burst | Application load, browser workload, connection or remote session |
| Only one game feels late | Game settings, frame delivery and bindings |
| Only Bluetooth mode feels late | Supported receiver or wired mode under the same conditions |
| A key occasionally produces two events | Double typing diagnosis |
Compare one variable at a time
- Save work and try a simple local text editor. A remote session adds another input path.
- Try a second browser or a clean profile with the same test. Keep the tab visible and focused.
- Close a known heavy task and repeat. Do not compare a quiet first run with a busy second run and attribute the difference to the keyboard.
- For wireless input, charge or replace batteries as appropriate, reconnect the receiver and follow the maker's placement guidance.
- If supported, compare wired, USB receiver and Bluetooth modes with the same keyboard, app and computer.
Record observations such as “first press after sleep delayed” or “only happens while this game loads.” These are more actionable than a single unexplained millisecond number.
Wireless comparison
Keep the keyboard in the same position and use the same app while comparing supported connection modes. Note whether the delay happens only after waking from idle, during continuous typing or when the receiver is behind the computer. Change one condition at a time so a difference has an explanation. If only wireless mode misbehaves, take those observations to the manufacturer before changing unrelated repeat or debounce settings.
Polling rate is not total latency
A frequency describes how often an update opportunity occurs. At 1000 Hz the interval is 1 ms, but that arithmetic does not say the whole input path takes 1 ms. Scanning, firmware, transport, scheduling and rendering also matter.
Timing gaps between human key presses or automatic repeats are not USB polling intervals. A web page does not see every empty hardware report. Comparing advertised polling rates requires device-specific measurements, not inverting the smallest gap between two key events.
What browser timestamps mean
An event timestamp belongs to the browser's timing system. Browser privacy settings can reduce its precision. Time from an event timestamp to a handler is not time from finger movement to display output; neither is the gap between successive taps.
For actual physical latency, use a test with a defined hardware trigger and a measured output, and report its method. See our methodology for the boundary of this site's measurements.
References
- MDN: Event.timeStamp explains timestamp origin and precision.
- Apple: keyboard response speed and Slow Keys.
- Microsoft: input-device troubleshooting.