polling rate

I read before that KB polling rate at 8K has a CPU impact but having ran game benchmarks back to back at both 8K and 1K I see no difference between benchmark runs and mashing the keys with both hands during each run. So I did the next test, high framerate recording of keypress to on-screen...

i have an issue when playing world of warcraft, where when i hold right mouse down to move the camera around etc after so many seconds it releases itself while im still holding it down and it only happens in wow and not on other games and ive tried everything except this.... is it safe and easy...