Camera close to transparency problem


I noticed that when I get close to transparent object I got huge FPS drops. For example, I put a fog and my player is going through it, or I ride through waterfall. If I am about 300 uu it is ok, but when I am really close, I have 37 FPS, just after I pass the particles it is back to normal. This is NOT related to the particles count etc but to the transparency material. I think Oculus has some real problems with them.