[2020] Rainbow Six Siege vulkan Insane RAM and GPU usage

Hello. I've got problems with vulkan. Actually it increases FPS a lot as an AMD user but when I play the game in vulkan it uses ram 2x more than DirectX and uses GPU 2X too. Too many apu users on amd side. We got an fps improvement but there is no ram left when we are playing. We can use directx 11 with less ram and gpu usage but fps goes lower too. Can you help us?(In APU Gpu uses Ram too so 8GB isn't enough) Have a nice day )))))