Mining and Threads

I have been looking up on the optimal amount of threads to use when mining with either CPU or GPU and from what I have gathered most people that have wrote something have said that less is better. One article that I have read said that when they tried out 16 threads that they would get about 100 to 150 h/s and when they did at 8 threads that it was almost 400 h/s. I am have been playing around with my CPU trying to see if it makes a difference and I have not seen that drastic amount of change when I lower amount threads. It seemed as I played around with it more threads got used but still not quite sure on what to make out on it all. I plan on diving down deeper and finding out more about this and I will post what I find about it on here.