Which is more performant, passing a method the entire object, or a property of that object?

Question

Consider the following example.

I need to check if a CouponModel has a unique serial key.

I have two choices:

CouponModel model = GetFromSomewhere();

if (!CouponHasUniqueKey(model))
{
}

//or

if (!CouponHasUniqueKey(model.SerialKey))
{
}

Of course in the method where I pass in the whole object I would have to access the string property instead of working directly with the string.

Which option is better and why?

Answer 1

I believe the performance will be the same.

I'd also prefer to give the responsibility to the object itself:

CouponModel coupon = GetFromSomewhere();
if (!coupon.HasUniqueKey()) {
  // ...
}