There is a very simple test in WOFF / WOTR to see if you are CPU or GPU bound.
Take note of you FPS looking straight ahead when flying a couple of thousand feet up, then look straight up at a clear sky and note your FPS again.
If your FPS dramatically rise, then you are GPU bound, if they stay about the same, you are CPU bound.
The reason is if you are CPU bound, it does not matter much where you look because the CPU has to keep track of everything happening in the game, so looking up does not make a big difference.
On the other hand, if you are GPU bound, your FPS will dramatically rise, because the GPU is drawing a clear sky versus all the terrain objects that you see straight ahead it is easier on the GPU, so higher FPS.