Ehm, there is an in-game tool for that. Bring up the console, and use
PerfOverlay.DrawGraph 1
In the bottom left corner of your screen you'll see a graph depicting CPU / GPU time on each frame.
I have a 6700K and a 1070ti.If I leave my FPS unlocked, it reaches 120-ish, but the stutter is horrible, I can see it on the CPU graph. CPU time spikes well up.
If I cap it to 100 or 90, the game feels a lot smoother, and the CPU time doesn't spike…