Hello, I found this difference between dx11 and dx9 DX11 DX9 In DX9 all full, fps are perfect, but DX11 less than 10 FPS. Thank you.
https://forum.studio-397.com/index.php?threads/official-dx9-vs-dx11-performance-difference.55385/ Do the benchmark according to the instructions in the topic I just linked to you.
Known problem, that the informations on this config-screen are wrong. However, rF2 works with the correct values of RAM/VRAM.