What is the reason behind this huge Performance difference in .Net 4

Question

I was just doing some research on RedBlack Tree. I knew that SortedSet class in .Net 4.0 uses RedBlack tree. So I took that part out as is using Reflector and created a RedBlack

Answer 1

You have a bug in your Node class. When you call the constructor that only takes a single value argument you should be setting IsRed to true.

I suppose that the fixed Node class should look something like this:

public sealed class Node
{
    public T Item { get; private set; }
    public bool IsRed { get; set; }
    public Node Left { get; set; }
    public Node Right { get; set; }

    public Node(T value)
    {
        Item = value;
        IsRed = true;
    }

    public Node(T value, bool isRed)
    {
        Item = value;
        IsRed = isRed;
    }
}

Another option -- my preference -- would be to omit that constructor altogether and always require IsRed to be set explicitly when you instantiate a new node:

public sealed class Node
{
    public T Item { get; private set; }
    public bool IsRed { get; set; }
    public Node Left { get; set; }
    public Node Right { get; set; }

    public Node(T value, bool isRed)
    {
        Item = value;
        IsRed = isRed;
    }
}

And then replace this line in your Add method...

Node current = new Node(item);

...with this...

Node current = new Node(item, true);