Creating high-performance code for any CPU using C# and C++/CLI

Creating high-performance code for any CPU using C# and C++/CLI

I'm creating a DirectX application with native C++ and using C++/CLI to
facilitate IPC with a C# application.
However, when it comes to building the entire solution; I'm confused about
how to make the system work for x86 and x64 CPU architectures, whilst
still maintaining as high-performance as possible.
I'm wary of (and want to avoid) any sort of emulation (e.g. WoW32/64).
Of course, I can compile the C# projects using AnyCPU. But then what do I
compile the C++ output as?
Do I just compile two separate builds; one for x86 and one for x64?
Thank you