diff --git a/websocket-sharp/Ext.cs b/websocket-sharp/Ext.cs
index 56628a39..3be026e6 100644
--- a/websocket-sharp/Ext.cs
+++ b/websocket-sharp/Ext.cs
@@ -1341,37 +1341,74 @@ namespace WebSocketSharp
 
     /// <summary>
     /// Retrieves a sub-array from the specified <paramref name="array"/>.
-    /// A sub-array starts at the specified element position.
+    /// A sub-array starts at the specified element position in <paramref name="array"/>.
     /// </summary>
     /// <returns>
-    /// An array of T that receives a sub-array, or an empty array of T if any problems
-    /// with the parameters.
+    /// An array of T that receives a sub-array, or an empty array of T
+    /// if any problems with the parameters.
     /// </returns>
     /// <param name="array">
-    /// An array of T that contains the data to retrieve a sub-array.
+    /// An array of T from which to retrieve a sub-array.
     /// </param>
     /// <param name="startIndex">
-    /// An <see cref="int"/> that contains the zero-based starting position of a sub-array
-    /// in <paramref name="array"/>.
+    /// An <see cref="int"/> that represents the zero-based starting position of
+    /// a sub-array in <paramref name="array"/>.
     /// </param>
     /// <param name="length">
-    /// An <see cref="int"/> that contains the number of elements to retrieve a sub-array.
+    /// An <see cref="int"/> that represents the number of elements to retrieve.
     /// </param>
     /// <typeparam name="T">
-    /// The type of elements in the <paramref name="array"/>.
+    /// The type of elements in <paramref name="array"/>.
     /// </typeparam>
     public static T[] SubArray<T> (this T[] array, int startIndex, int length)
     {
-      if (array == null || array.Length == 0)
+      int len;
+      if (array == null || (len = array.Length) == 0)
         return new T[0];
 
-      if (startIndex < 0 || length <= 0)
+      if (startIndex < 0 || length <= 0 || startIndex + length > len)
         return new T[0];
 
-      if (startIndex + length > array.Length)
+      if (startIndex == 0 && length == len)
+        return array;
+
+      var subArray = new T[length];
+      Array.Copy (array, startIndex, subArray, 0, length);
+
+      return subArray;
+    }
+
+    /// <summary>
+    /// Retrieves a sub-array from the specified <paramref name="array"/>.
+    /// A sub-array starts at the specified element position in <paramref name="array"/>.
+    /// </summary>
+    /// <returns>
+    /// An array of T that receives a sub-array, or an empty array of T
+    /// if any problems with the parameters.
+    /// </returns>
+    /// <param name="array">
+    /// An array of T from which to retrieve a sub-array.
+    /// </param>
+    /// <param name="startIndex">
+    /// A <see cref="long"/> that represents the zero-based starting position of
+    /// a sub-array in <paramref name="array"/>.
+    /// </param>
+    /// <param name="length">
+    /// A <see cref="long"/> that represents the number of elements to retrieve.
+    /// </param>
+    /// <typeparam name="T">
+    /// The type of elements in <paramref name="array"/>.
+    /// </typeparam>
+    public static T[] SubArray<T> (this T[] array, long startIndex, long length)
+    {
+      long len;
+      if (array == null || (len = array.LongLength) == 0)
         return new T[0];
 
-      if (startIndex == 0 && array.Length == length)
+      if (startIndex < 0 || length <= 0 || startIndex + length > len)
+        return new T[0];
+
+      if (startIndex == 0 && length == len)
         return array;
 
       var subArray = new T[length];
diff --git a/websocket-sharp/PayloadData.cs b/websocket-sharp/PayloadData.cs
index d1a473dc..9334b52f 100644
--- a/websocket-sharp/PayloadData.cs
+++ b/websocket-sharp/PayloadData.cs
@@ -37,11 +37,11 @@ namespace WebSocketSharp
   {
     #region Private Fields
 
-    private byte[] _appData;
-    private ulong  _appDataLength;
-    private byte[] _extData;
-    private ulong  _extDataLength;
-    private bool   _masked;
+    private byte[]                 _data;
+    private static readonly byte[] _empty;
+    private long                   _extDataLength;
+    private long                   _length;
+    private bool                   _masked;
 
     #endregion
 
@@ -51,49 +51,52 @@ namespace WebSocketSharp
 
     #endregion
 
+    #region Static Constructor
+
+    static PayloadData ()
+    {
+      _empty = new byte[0];
+    }
+
+    #endregion
+
     #region Internal Constructors
 
     internal PayloadData ()
-      : this (new byte[0], new byte[0], false)
+    {
+      _data = _empty;
+    }
+
+    internal PayloadData (byte[] data)
+      : this (data, false)
     {
     }
 
-    internal PayloadData (byte[] applicationData)
-      : this (new byte[0], applicationData, false)
+    internal PayloadData (byte[] data, bool masked)
     {
-    }
-
-    internal PayloadData (string applicationData)
-      : this (new byte[0], Encoding.UTF8.GetBytes (applicationData), false)
-    {
-    }
-
-    internal PayloadData (byte[] applicationData, bool masked)
-      : this (new byte[0], applicationData, masked)
-    {
-    }
-
-    internal PayloadData (byte[] extensionData, byte[] applicationData, bool masked)
-    {
-      _extDataLength = (ulong) extensionData.LongLength;
-      _appDataLength = (ulong) applicationData.LongLength;
-      if (_appDataLength > MaxLength - _extDataLength)
-        throw new ArgumentOutOfRangeException (
-          "The total length of 'extensionData' and 'applicationData' is greater than the allowable length.");
-
-      _extData = extensionData;
-      _appData = applicationData;
+      _data = data;
       _masked = masked;
+      _length = data.LongLength;
     }
 
     #endregion
 
     #region Internal Properties
 
+    internal long ExtensionDataLength {
+      get {
+        return _extDataLength;
+      }
+
+      set {
+        _extDataLength = value;
+      }
+    }
+
     internal bool IncludesReservedCloseStatusCode {
       get {
-        return _appDataLength > 1 &&
-               _appData.SubArray (0, 2).ToUInt16 (ByteOrder.Big).IsReserved ();
+        return _length > 1 &&
+               _data.SubArray (0, 2).ToUInt16 (ByteOrder.Big).IsReserved ();
       }
     }
 
@@ -103,13 +106,17 @@ namespace WebSocketSharp
 
     public byte[] ApplicationData {
       get {
-        return _appData;
+        return _extDataLength > 0
+               ? _data.SubArray (_extDataLength, _length - _extDataLength)
+               : _data;
       }
     }
 
     public byte[] ExtensionData {
       get {
-        return _extData;
+        return _extDataLength > 0
+               ? _data.SubArray (0, _extDataLength)
+               : _empty;
       }
     }
 
@@ -121,31 +128,18 @@ namespace WebSocketSharp
 
     public ulong Length {
       get {
-        return _extDataLength + _appDataLength;
+        return (ulong) _length;
       }
     }
 
     #endregion
 
-    #region Private Methods
-
-    private static void mask (byte[] source, byte[] key)
-    {
-      for (long i = 0; i < source.LongLength; i++)
-        source[i] = (byte) (source[i] ^ key[i % 4]);
-    }
-
-    #endregion
-
     #region Internal Methods
 
     internal void Mask (byte[] key)
     {
-      if (_extDataLength > 0)
-        mask (_extData, key);
-
-      if (_appDataLength > 0)
-        mask (_appData, key);
+      for (long i = 0; i < _length; i++)
+        _data[i] = (byte) (_data[i] ^ key[i % 4]);
 
       _masked = !_masked;
     }
@@ -156,23 +150,18 @@ namespace WebSocketSharp
 
     public IEnumerator<byte> GetEnumerator ()
     {
-      foreach (var b in _extData)
-        yield return b;
-
-      foreach (var b in _appData)
+      foreach (var b in _data)
         yield return b;
     }
 
     public byte[] ToByteArray ()
     {
-      return _extDataLength > 0
-             ? new List<byte> (this).ToArray ()
-             : _appData;
+      return _data;
     }
 
     public override string ToString ()
     {
-      return BitConverter.ToString (ToByteArray ());
+      return BitConverter.ToString (_data);
     }
 
     #endregion