Also, while most games are fine with losing a frame or two every few minutes, in VR dropping frames will cause motion sickness really fast. FPS is, from what I've observed, the most important part of a VR game. If you're dropping frames or stuttering, the experience will suffer greatly

When I was developing a VR game, my team noticed that some ultra-sensitive people started to get sick when we would drop around five frames (the vive displays 90, so this is only a ~5% drop). There was more to it (dropping a few frames every few minutes was usually fine, but consistently dropping frames every second or two is an issue).