I can completely relate to your questioning =)
Playing in Non-VR mode now and still stutters. Seems to get worse when things are flying around and there are explosions.
On a second play thru, it seems to get worse, sadly. I would bet on the physics engine taking too much time and starving the audio buffers.
Any other test you might want me to perform? Feel free to ask.
What did you use? Unreal? Unity?