You’re correct, where I got confused is the lazy per-method JIT and the tiers of JIT optimization. My understanding is that dotnet only compiles on first function call, or when it has to for things like generics. So, some code is never compiled if it’s never executed. And then, functions will be re-JIT at higher optimization levels under certain conditions later. You certainly know more about this than me, but yes I was wrong about conditional JIT.