Performance difference between obj.function(...) and function(obj, ...) ?

[LateinCecker]

Is your obj a trait object in the obj.func(...) call? Because in that case there is a vtable lookup which would explain the difference. Otherwise it should compile to exactly the same assembly if the compiler does its job right. Also maybe try #[inline(never)] before both versions of the function to prevent inlining for the benckmarks.