Consistent, periodic frame drop roughly once per second (on 1080 / 5820k)

Regardless of settings, I consistently get a few dropped frames based on some CPU issue every second or so - frame timing chart here:This basically renders the game unplayable. I haven't had this happen in any other VR game, and I have found no reliable way to eliminate or even influence it. I hope you can identify and fix it, if you need any additional information let me know.