[sp332]

The PS/2 protocol is incredibly slow. Just sending two bytes over the wire via PS/2 takes 1.3 ms.

[ComputerGuru]

True. But that is throughout, not latency. Key presses are latency limited, not bandwidth limited.

[sp332]

But the latency of your keyboard will be increased by 1.3 ms just by putting it on a PS/2 port. That's more than USB polling at 1000Hz.