I've always used conservative or ondemand for CPU frequency governors, but after reading Matthew Garrett's post on modern cpus, and how they consume energy at idle and various frequency states, I learned that its sometimes more efficient to get the processing over with faster. This method allows the cpu to do what it needs to do faster, and then return to an idle state, thanks to the tickless kernel.
My Macbook has decent power states with ondemand, and now I'm trying performance. Either way, most of all I'd really like to get my laptop cooler. It gets too hot to be comfortable, even when I'm simply typing a blog post, like right now. :-( I usually use a cooler pad, but I don't have one at the moment.