here it is.., it is at 100% at the moment but as you lessen it, it will take the load off your computer and you can easily move about the scene. what will happen is the hair (or any paint effects) will LOOK less but makes completely no difference to the render, all the hair is still there even if you have it at 1 % and can hardly see anything.., i use this method every time I use any paint effects.
take it easy and life will be easy