Because the switches rely on light and not a piece of metal, as soon as the beam is broken, the switch responds and you see your output.
It's a minor point, but it's frustrating constantly adjusting the wrist rest because you happened to knock the desk or make any other unintended impacts.
It has exceptionally low latency, and the Razer Linear Optical switches on our unit feel light and very responsive thanks to their low operating force and short pre-travel distance.