Hair can potentially bring ANY system to it's knees in pain during a render because of its complexity. Like all things in the 3D world, an intelligent use of the tools is critical to getting good effects/renders and reasonable render times. That's where we get to be artists/craftsman, right? The master of our tools... ;-) I don't see people getting the latest word-processor software complaining that it doesn't help them write better poetry - automatically. :-D