I've been led to believe that casting can, in certain circumstances, become a measurable hindrance on performance. This may be moreso the case when we start dealing with incoherent webs of nasty exception throwing\catching.

Given that I wish to create more correct heuristics when it comes to programming, I've been prompted to ask this question to the .NET gurus out there: Is interface casting faster than class casting?

To give a code example, let's say this exists:

public interface IEntity { IParent DaddyMommy { get; } }
public interface IParent : IEntity { }
public class Parent : Entity, IParent { }
public class Entity : IEntity
{
    public IParent DaddyMommy { get; protected set; }
    public IParent AdamEve_Interfaces
    {
        get
        {
            IEntity e = this;
            while (this.DaddyMommy != null)
                e = e.DaddyMommy as IEntity;
            return e as IParent;
        }   
    }
    public Parent AdamEve_Classes
    {
        get
        {
            Entity e = this;
            while (this.DaddyMommy != null)
                e = e.DaddyMommy as Entity;
            return e as Parent;
        }
    }
}

So, is AdamEve_Interfaces faster than AdamEve_Classes? If so, by how much? And, if you know the answer, why?