[SOLVED] Big CPU usage on GeForce 8800 GT

using System;
using System.Collections.Generic;
using OpenTK;
using OpenTK.Graphics;
using OpenTK.Graphics.OpenGL;
using OpenTK.Input;
 
using OpenTK.Platform;
 
namespace ngine
{
    public class Game : GameWindow
    {
        public Game() : base(800, 600){}
 
        protected override void OnLoad(EventArgs e)
        {
            base.OnLoad(e);
            VSync = VSyncMode.On;
            Mouse.Move += new EventHandler<MouseMoveEventArgs>(Mouse_Move);
        }
 
        void Mouse_Move(object sender, MouseMoveEventArgs e)
        {
            if (!Mouse[MouseButton.Right]) return;
            Title = "X: "+Mouse.X + " Y: " + Mouse.Y;
        }
 
        protected override void OnUpdateFrame(FrameEventArgs e)
        {
            base.OnUpdateFrame(e);
            CursorVisible = !Mouse[MouseButton.Right];
            System.Threading.Thread.Sleep(1);
        }
 
        protected override void OnRenderFrame(FrameEventArgs fea)
        {
            base.OnRenderFrame(fea);
            GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);
            SwapBuffers();
            System.Threading.Thread.Sleep(1);
        }
 
        [STAThread]
        public static void Main()
        {
            using (Game example = new Game())
            {
                example.Run(60);
            }
        }
    }
}