Even with a monster PC, the hair is one of the things that really eats up the frames in VaM.
But IMHO the shader quality is only a small thing compared to a ridiculous high hair segment count of some hair styles.
Every time I use a new downloaded hairstyle, I usually open up the hair settings and crank down the performance heavy physics settings as low as possible. And even with this… some hair styles are created with enormous settings and multiple parts right from the start. Those hairstyles, no matter how good they may look, should be IMHO avoided with slow PCs, especially in VR.