Dx11 legacy must be selected to enter the game?

After my software settings are completed, I must select the old version of Dx11 to enter the game. If I use dx12, the screen is very catchy. Where did I set it wrong?

Why is it very slow to use isboxer to enter the game. Dx11 (old version) must be selected. It will be better. It won't happen before. Isboxer, where did I set it wrong?