I don’t think this is an achievable goal for a kernel, since it has strictly more permissions than user code. There are some parts of user code that simply cann

I don’t think this is an achievable goal for a kernel, since it has strictly more permissions than user code. There are some parts of user code that simply cannot be made faster by changing how they’re written: no amount of rewriting in Rust/C/C++ will help if the relevant kernel primitives are not there. The kernel must move with the times, and incorporate new features as they are (tastefully) decided upon.