Surface 3 laptop keyboard latency problem

Run the Surface Diagnostic Tool.

Settings → Accessibility → Keyboard → Filter Keys = OFF

Go to Windows Update → Advanced options → Optional updates

Install everything related to:

Surface firmware

Keyboard / HID drivers

Boot into UEFI (Volume Up + Power)

Lag in UEFI → hardware issue (very likely)

Smooth in UEFI → Windows issue

Use the working external Bluetooth keyboard as a baseline and focus troubleshooting on the built-in keyboard and system configuration.

Follow this path:

1. Check for Windows and firmware updates
   Latency can be caused by outdated drivers or firmware. Ensure the Surface Laptop 3 is fully updated:
   • Select Start > Settings > Update & Security > Windows Update and install all available updates.
   • If it is not a Surface-branded device, also check the OEM’s support site, but for Surface this step is usually sufficient.
2. Test for software vs. hardware issue
   • Close all open apps and test typing again. If latency improves, app load or background processes may be interfering with input.
   • Restart the PC to refresh drivers and services, then test the built-in keyboard immediately after sign-in, before opening other apps.
   • If possible, test the keyboard behavior in Safe Mode. If it works normally there, a third-party app or driver is likely causing the latency.
3. Compare with external keyboard behavior
   • Since the Bluetooth keyboard works fine, keep it connected and type in the same app or window with both keyboards.
   • If latency occurs only with the built-in keyboard and not with Bluetooth in the same scenario, this points more strongly to a built-in keyboard hardware or firmware issue.
4. Check for intermittent key issues
   • If some keys sometimes lag or fail to register, debris under keys can cause intermittent issues. Use compressed air to blow under the affected keys and wipe the keyboard with a slightly damp microfiber cloth.
   • If an external USB or Bluetooth keyboard shows no latency while the built-in one does, and cleaning plus updates do not help, the built-in keyboard may have a hardware fault.
5. Rule out NumLock / layout anomalies
   • If keys are producing unexpected characters or behavior along with latency, verify that NumLock or function-lock features are not changing key mappings.
   • Confirm the input language and layout: Start > Settings > Time & language > Region & language, and ensure the keyboard input language matches the display language.
6. If the issue persists
   • After updates, restart, app-closure, cleaning, and layout checks, if the built-in keyboard still has severe latency while external keyboards are fine, treat it as likely hardware-related and contact support or a technician for inspection of the Surface Laptop 3 keyboard assembly.

References:

• Troubleshoot problems with your Surface mouse or keyboard
• Keyboard keys malfunctioning - Microsoft Q&A
• Why won't my keyboard work when I power up my laptop? - Microsoft Q&A
• keypad issue - Microsoft Q&A