It really always was, the runtime system within .NET always had the capability to run C/C++ code but to get C++ code to talk to C#/VB code with GC-heap objects you had to use language extensions and I think that limited the appeal by a fair bit (Especially as iirc they actually made 2 different extensions), on top of this the C# language has also always had and continually gets new extensions to do non-heap tasks (Compared to Java that has focused on the a clean Java world where everything was on the heap).

If it can be performant depends on the tasks it need to full fill.

The Switch uses the X1. A chip from 2015. The CPU has a clock rate of 1GZ, the GPU 307-768 MHz. [1]

[1] https://en.wikipedia.org/wiki/Nintendo_Switch#Technical_spec...

Their C# JIT [1] generates x86_64 or ARM native code. This is why it's fast.

1: https://github.com/Ryujinx/Ryujinx/tree/master/src/ARMeilleu...

Check the end of the article for frame rates for different titles.