Increase keyboard repeat rate beyond control panel limits in Windows 10

To get around this you could use the "Filter Keys" feature in the Ease of Access center to speed it up. Of course backup your registry before doing this or at least back up the values so you can roll it back if it isn't doing what you want it to do. Go into regedit.exe navigate down to HKEY_CURRENT_USER\Control Panel\Accessibility\Keyboard Response and update your values. Reboot for the changes to be seen.

[HKEY_CURRENT_USER\Control Panel\Accessibility\Keyboard Response]
"AutoRepeatDelay"="200" 
"AutoRepeatRate"="6" 
"DelayBeforeAcceptance"="0" 
"Flags"="59" 
"BounceTime"="0"