This is what happens if you connect two devices to one USB controller: the polling rate is unstable.
IPI Aurora65 8khz Keyboard
Wlmouse Ying (red) 8khz Mouse
This is what happens if you connect two devices to one USB controller: the polling rate is unstable.
In that case, buy a 14900ks, remove all limits, cool it with a chiller, and move to a location where the game servers are located. Play with 0 ping and 1000 FPS. This way, you'll get 1 ms of input lag.