enabled SIO_LOOPBACK_FAST_PATH on win8/server2012 (via jepickett)

StackExchange.Redis/StackExchange/Redis/SocketManager.cs

@@ -121,10 +121,30 @@ public void Dispose()
         internal SocketToken BeginConnect(EndPoint endpoint, ISocketCallback callback)
         {
             var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+            SetFastLoopbackOption(socket);
             socket.NoDelay = true;
             socket.BeginConnect(endpoint, EndConnect, Tuple.Create(socket, callback));
             return new SocketToken(socket);
         }
+        internal void SetFastLoopbackOption(Socket socket)
+        {
+            // SIO_LOOPBACK_FAST_PATH (http://msdn.microsoft.com/en-us/library/windows/desktop/jj841212%28v=vs.85%29.aspx)
+            // Speeds up localhost operations significantly. OK to apply to a socket that will not be hooked up to localhost, 
+            // or will be subject to WFP filtering.
+            const int SIO_LOOPBACK_FAST_PATH = -1744830448;
+
+            // windows only
+            if (Environment.OSVersion.Platform == PlatformID.Win32NT)
+            {
+                // Win8/Server2012+ only
+                var osVersion = Environment.OSVersion.Version;
+                if (osVersion.Major > 6 || osVersion.Major == 6 && osVersion.Minor >= 2)
+                {
+                    byte[] optionInValue = BitConverter.GetBytes(1);
+                    socket.IOControl(SIO_LOOPBACK_FAST_PATH, optionInValue, null);
+                }
+            }
+        }
 
         internal void RequestWrite(PhysicalBridge bridge, bool forced)
         {