Foreach with functions being passed being slower is an implementation detail. You don't see it in Rust, where the block body is inlined like a generic, and it's

Foreach with functions being passed being slower is an implementation detail. You don't see it in Rust, where the block body is inlined like a generic, and it's perfectly feasible for a dynamic runtime to specialize the pattern and inline based on it being a common practice, never mind polymorphic inline caches which in principle permit inlining in this case.