(Skip to 0:39, I've also added MSI monitoring in the video)
I've had this issue probably from the beta, it always happens at the start of rounds when I hit someone or someone hits me back. The game is otherwise smooth, but the general stuttering that I get in SP and MP is somehow related to hitting someone or being hit.
i7-2600K OC'd to 4.1.
8 GB DDR3.
Game is on HDD.
Capped at 70 with RTSS.