CLR-style just-in-time monomorphization is plenty performant: in fact, it's just about ideal. It's also not that difficult when you have a JIT when compared to the complexity you need for speculative optimizations of hot spots anyway.
In any case, the .NET approach isn't an option for AOT compilers like those of Go. For Go, the only reasonable option is ahead of time monomorphization, which really isn't that bad.
In any case, the .NET approach isn't an option for AOT compilers like those of Go. For Go, the only reasonable option is ahead of time monomorphization, which really isn't that bad.