diff --git a/shadowsocks-csharp/Controller/Service/PortForwarder.cs b/shadowsocks-csharp/Controller/Service/PortForwarder.cs
index 5429b053..46ec9733 100644
--- a/shadowsocks-csharp/Controller/Service/PortForwarder.cs
+++ b/shadowsocks-csharp/Controller/Service/PortForwarder.cs
@@ -7,11 +7,11 @@ namespace Shadowsocks.Controller
 {
     class PortForwarder : Listener.Service
     {
-        int _targetPort;
+        private readonly int _targetPort;
 
         public PortForwarder(int targetPort)
         {
-            this._targetPort = targetPort;
+            _targetPort = targetPort;
         }
 
         public override bool Handle(byte[] firstPacket, int length, Socket socket, object state)
@@ -20,11 +20,11 @@ namespace Shadowsocks.Controller
             {
                 return false;
             }
-            new Handler().Start(firstPacket, length, socket, this._targetPort);
+            new Handler().Start(firstPacket, length, socket, _targetPort);
             return true;
         }
 
-        class Handler
+        private class Handler
         {
             private byte[] _firstPacket;
             private int _firstPacketLength;
@@ -33,7 +33,7 @@ namespace Shadowsocks.Controller
             private bool _closed = false;
             private bool _localShutdown = false;
             private bool _remoteShutdown = false;
-            public const int RecvSize = 16384;
+            private const int RecvSize = 2048;
             // remote receive buffer
             private byte[] remoteRecvBuffer = new byte[RecvSize];
             // connection receive buffer
@@ -44,9 +44,9 @@ namespace Shadowsocks.Controller
 
             public void Start(byte[] firstPacket, int length, Socket socket, int targetPort)
             {
-                this._firstPacket = firstPacket;
-                this._firstPacketLength = length;
-                this._local = socket;
+                _firstPacket = firstPacket;
+                _firstPacketLength = length;
+                _local = socket;
                 try
                 {
                     EndPoint remoteEP = SocketUtil.GetEndPoint("127.0.0.1", targetPort);
@@ -58,7 +58,7 @@ namespace Shadowsocks.Controller
                 catch (Exception e)
                 {
                     Logging.LogUsefulException(e);
-                    this.Close();
+                    Close();
                 }
             }
 
@@ -77,7 +77,7 @@ namespace Shadowsocks.Controller
                 catch (Exception e)
                 {
                     Logging.LogUsefulException(e);
-                    this.Close();
+                    Close();
                 }
             }
 
@@ -89,12 +89,12 @@ namespace Shadowsocks.Controller
                 }
                 try
                 {
-                    _remote.BeginSend(_firstPacket, 0, _firstPacketLength, 0, new AsyncCallback(StartPipe), null);
+                    _remote.BeginSend(_firstPacket, 0, _firstPacketLength, 0, StartPipe, null);
                 }
                 catch (Exception e)
                 {
                     Logging.LogUsefulException(e);
-                    this.Close();
+                    Close();
                 }
             }
 
@@ -108,14 +108,14 @@ namespace Shadowsocks.Controller
                 {
                     _remote.EndSend(ar);
                     _remote.BeginReceive(remoteRecvBuffer, 0, RecvSize, 0,
-                        new AsyncCallback(PipeRemoteReceiveCallback), null);
+                        PipeRemoteReceiveCallback, null);
                     _local.BeginReceive(connetionRecvBuffer, 0, RecvSize, 0,
-                        new AsyncCallback(PipeConnectionReceiveCallback), null);
+                        PipeConnectionReceiveCallback, null);
                 }
                 catch (Exception e)
                 {
                     Logging.LogUsefulException(e);
-                    this.Close();
+                    Close();
                 }
             }
 
@@ -128,10 +128,9 @@ namespace Shadowsocks.Controller
                 try
                 {
                     int bytesRead = _remote.EndReceive(ar);
-
                     if (bytesRead > 0)
                     {
-                        _local.BeginSend(remoteRecvBuffer, 0, bytesRead, 0, new AsyncCallback(PipeConnectionSendCallback), null);
+                        _local.BeginSend(remoteRecvBuffer, 0, bytesRead, 0, PipeConnectionSendCallback, null);
                     }
                     else
                     {
@@ -143,7 +142,7 @@ namespace Shadowsocks.Controller
                 catch (Exception e)
                 {
                     Logging.LogUsefulException(e);
-                    this.Close();
+                    Close();
                 }
             }
 
@@ -156,10 +155,9 @@ namespace Shadowsocks.Controller
                 try
                 {
                     int bytesRead = _local.EndReceive(ar);
-
                     if (bytesRead > 0)
                     {
-                        _remote.BeginSend(connetionRecvBuffer, 0, bytesRead, 0, new AsyncCallback(PipeRemoteSendCallback), null);
+                        _remote.BeginSend(connetionRecvBuffer, 0, bytesRead, 0, PipeRemoteSendCallback, null);
                     }
                     else
                     {
@@ -171,7 +169,7 @@ namespace Shadowsocks.Controller
                 catch (Exception e)
                 {
                     Logging.LogUsefulException(e);
-                    this.Close();
+                    Close();
                 }
             }
 
@@ -184,13 +182,13 @@ namespace Shadowsocks.Controller
                 try
                 {
                     _remote.EndSend(ar);
-                    _local.BeginReceive(this.connetionRecvBuffer, 0, RecvSize, 0,
-                        new AsyncCallback(PipeConnectionReceiveCallback), null);
+                    _local.BeginReceive(connetionRecvBuffer, 0, RecvSize, 0,
+                        PipeConnectionReceiveCallback, null);
                 }
                 catch (Exception e)
                 {
                     Logging.LogUsefulException(e);
-                    this.Close();
+                    Close();
                 }
             }
 
@@ -203,13 +201,13 @@ namespace Shadowsocks.Controller
                 try
                 {
                     _local.EndSend(ar);
-                    _remote.BeginReceive(this.remoteRecvBuffer, 0, RecvSize, 0,
-                        new AsyncCallback(PipeRemoteReceiveCallback), null);
+                    _remote.BeginReceive(remoteRecvBuffer, 0, RecvSize, 0,
+                        PipeRemoteReceiveCallback, null);
                 }
                 catch (Exception e)
                 {
                     Logging.LogUsefulException(e);
-                    this.Close();
+                    Close();
                 }
             }
 
@@ -217,7 +215,7 @@ namespace Shadowsocks.Controller
             {
                 if (_localShutdown && _remoteShutdown)
                 {
-                    this.Close();
+                    Close();
                 }
             }