diff --git a/lib/delphi/src/Thrift.Protocol.Compact.pas b/lib/delphi/src/Thrift.Protocol.Compact.pas
index 665cfc4..424b267 100644
--- a/lib/delphi/src/Thrift.Protocol.Compact.pas
+++ b/lib/delphi/src/Thrift.Protocol.Compact.pas
@@ -80,6 +80,9 @@
       STRUCT        = $0C
     );
 
+  private type
+    TEightBytesArray = packed array[0..7] of Byte;
+
   strict private const
     ttypeToCompactType : array[TType] of Types = (
       Types.STOP,           // Stop    = 0,
@@ -190,7 +193,7 @@
     class function intToZigZag( const n : Integer) : Cardinal;
 
     //Convert a Int64 into little-endian bytes in buf starting at off and going until off+7.
-    class procedure fixedLongToBytes( const n : Int64; var buf : TBytes);
+    class procedure fixedLongToBytes( const n : Int64; var buf : TEightBytesArray); inline;
 
   strict protected
     function GetMinSerializedSize( const aType : TType) : Integer;  override;
@@ -240,7 +243,7 @@
     // Note that it's important that the mask bytes are Int64 literals,
     // otherwise they'll default to ints, and when you shift an Integer left 56 bits,
     // you just get a messed up Integer.
-    class function bytesToLong( const bytes : TBytes) : Int64;
+    class function bytesToLong( const bytes : TEightBytesArray) : Int64; inline;
 
     // type testing and converting
     class function isBoolType( const b : byte) : Boolean;
@@ -319,10 +322,9 @@
 
 // Write an i32 as a varint. Results in 1-5 bytes on the wire.
 procedure TCompactProtocolImpl.WriteVarint32( n : Cardinal);
-var i32buf : TBytes;
-    idx : Integer;
+var idx : Integer;
+    i32buf : packed array[0..4] of Byte;
 begin
-  SetLength( i32buf, 5);
   idx := 0;
   while TRUE do begin
     ASSERT( idx < Length(i32buf));
@@ -339,7 +341,7 @@
     n := n shr 7;
   end;
 
-  Transport.Write( i32buf, 0, idx);
+  Transport.Write( @i32buf[0], 0, idx);
 end;
 
 
@@ -521,10 +523,10 @@
 
 // Write a double to the wire as 8 bytes.
 procedure TCompactProtocolImpl.WriteDouble( const dub: Double);
-var data : TBytes;
+var data : TEightBytesArray;
 begin
   fixedLongToBytes( DoubleToInt64Bits(dub), data);
-  Transport.Write( data);
+  Transport.Write( @data[0], 0, SizeOf(data));
 end;
 
 
@@ -580,10 +582,9 @@
 
 // Write an i64 as a varint. Results in 1-10 bytes on the wire.
 procedure TCompactProtocolImpl.WriteVarint64( n : UInt64);
-var varint64out : TBytes;
-    idx : Integer;
+var idx : Integer;
+    varint64out : packed array[0..9] of Byte;
 begin
-  SetLength( varint64out, 10);
   idx := 0;
   while TRUE do begin
     ASSERT( idx < Length(varint64out));
@@ -600,7 +601,7 @@
     n := n shr 7;
   end;
 
-  Transport.Write( varint64out, 0, idx);
+  Transport.Write( @varint64out[0], 0, idx);
 end;
 
 
@@ -627,9 +628,9 @@
 
 
 // Convert a Int64 into 8 little-endian bytes in buf
-class procedure TCompactProtocolImpl.fixedLongToBytes( const n : Int64; var buf : TBytes);
+class procedure TCompactProtocolImpl.fixedLongToBytes( const n : Int64; var buf : TEightBytesArray);
 begin
-  SetLength( buf, 8);
+  ASSERT( Length(buf) >= 8);
   buf[0] := Byte( n         and $FF);
   buf[1] := Byte((n shr 8)  and $FF);
   buf[2] := Byte((n shr 16) and $FF);
@@ -829,11 +830,11 @@
 
 
 // No magic here - just Read a double off the wire.
-function TCompactProtocolImpl.ReadDouble:Double;
-var longBits : TBytes;
+function TCompactProtocolImpl.ReadDouble : Double;
+var longBits : TEightBytesArray;
 begin
-  SetLength( longBits, 8);
-  Transport.ReadAll( longBits, 0, 8);
+  ASSERT( SizeOf(longBits) = SizeOf(result));
+  Transport.ReadAll( @longBits[0], SizeOf(longBits), 0, SizeOf(longBits));
   result := Int64BitsToDouble( bytesToLong( longBits));
 end;
 
@@ -934,7 +935,7 @@
 // Note that it's important that the mask bytes are Int64 literals,
 // otherwise they'll default to ints, and when you shift an Integer left 56 bits,
 // you just get a messed up Integer.
-class function TCompactProtocolImpl.bytesToLong( const bytes : TBytes) : Int64;
+class function TCompactProtocolImpl.bytesToLong( const bytes : TEightBytesArray) : Int64;
 begin
   ASSERT( Length(bytes) >= 8);
   result := (Int64(bytes[7] and $FF) shl 56) or
@@ -1104,7 +1105,7 @@
 procedure TestLongBytes;
 
   procedure Test( const test : Int64);
-  var buf : TBytes;
+  var buf : TCompactProtocolImpl.TEightBytesArray;
   begin
     TCompactProtocolImpl.fixedLongToBytes( test, buf);
     ASSERT( TCompactProtocolImpl.bytesToLong( buf) = test, IntToStr(test));
diff --git a/lib/delphi/src/Thrift.Protocol.JSON.pas b/lib/delphi/src/Thrift.Protocol.JSON.pas
index 61cad8b..515d85c 100644
--- a/lib/delphi/src/Thrift.Protocol.JSON.pas
+++ b/lib/delphi/src/Thrift.Protocol.JSON.pas
@@ -32,6 +32,7 @@
   Thrift.Configuration,
   Thrift.Transport,
   Thrift.Protocol,
+  Thrift.Stream,
   Thrift.Utils;
 
 type
@@ -832,7 +833,7 @@
 
 
 function TJSONProtocolImpl.ReadJSONString( skipContext : Boolean) : TBytes;
-var buffer : TMemoryStream;
+var buffer : TThriftMemoryStream;
     ch  : Byte;
     wch : Word;
     highSurogate: Char;
@@ -841,7 +842,7 @@
     tmp : TBytes;
 begin
   highSurogate := #0;
-  buffer := TMemoryStream.Create;
+  buffer := TThriftMemoryStream.Create;
   try
     if not skipContext
     then FContext.Read;
diff --git a/lib/delphi/src/Thrift.Serializer.pas b/lib/delphi/src/Thrift.Serializer.pas
index cb62603..8ee8a35 100644
--- a/lib/delphi/src/Thrift.Serializer.pas
+++ b/lib/delphi/src/Thrift.Serializer.pas
@@ -38,7 +38,7 @@
   // Generic utility for easily serializing objects into a byte array or Stream.
   TSerializer = class
   strict private
-    FStream    : TMemoryStream;
+    FStream    : TThriftMemoryStream;
     FTransport : ITransport;
     FProtocol  : IProtocol;
 
@@ -59,7 +59,7 @@
   // Generic utility for easily deserializing objects from byte array or Stream.
   TDeserializer = class
   strict private
-    FStream    : TMemoryStream;
+    FStream    : TThriftMemoryStream;
     FTransport : ITransport;
     FProtocol  : IProtocol;
 
@@ -92,7 +92,7 @@
 begin
   inherited Create;
 
-  FStream    := TMemoryStream.Create;
+  FStream    := TThriftMemoryStream.Create;
   adapter    := TThriftStreamAdapterDelphi.Create( FStream, FALSE);
 
   FTransport := TStreamTransportImpl.Create( nil, adapter, aConfig);
@@ -170,7 +170,7 @@
 begin
   inherited Create;
 
-  FStream    := TMemoryStream.Create;
+  FStream    := TThriftMemoryStream.Create;
   adapter    := TThriftStreamAdapterDelphi.Create( FStream, FALSE);
 
   FTransport := TStreamTransportImpl.Create( adapter, nil, aConfig);
diff --git a/lib/delphi/src/Thrift.Stream.pas b/lib/delphi/src/Thrift.Stream.pas
index 1668059..6c1320d 100644
--- a/lib/delphi/src/Thrift.Stream.pas
+++ b/lib/delphi/src/Thrift.Stream.pas
@@ -108,10 +108,52 @@
     constructor Create( const aStream: IStream);
   end;
 
+
+  TThriftMemoryStream = class(TMemoryStream)
+  strict protected
+    FInitialCapacity : NativeInt;
+  public
+    constructor Create( const aInitialCapacity : NativeInt = 4096);
+
+    // reimplemented
+    procedure Clear;
+
+    // make it publicly visible
+    property Capacity;
+  end;
+
+
+
 implementation
 
 uses Thrift.Transport;
 
+
+{ TThriftMemoryStream }
+
+constructor TThriftMemoryStream.Create( const aInitialCapacity : NativeInt);
+begin
+  inherited Create;
+  FInitialCapacity := aInitialCapacity;
+  Clear;
+end;
+
+
+procedure TThriftMemoryStream.Clear;
+// reimplemented to keep initial capacity
+begin
+  Position := 0;
+  Size     := 0;
+
+  // primary goal: minimize costly reallocations (performance!)
+  // secondary goal: prevent costly ressource over-allocations
+  if (FInitialCapacity >= 1024*1024)        // if we are talking about MB
+  or ((Capacity div 2) > FInitialCapacity)  // or the allocated buffer is really large
+  or (Capacity < FInitialCapacity)          // or we are actually below the limit
+  then Capacity := FInitialCapacity;
+end;
+
+
 { TThriftStreamAdapterCOM }
 
 procedure TThriftStreamAdapterCOM.Close;
diff --git a/lib/delphi/src/Thrift.Transport.MsxmlHTTP.pas b/lib/delphi/src/Thrift.Transport.MsxmlHTTP.pas
index 6704c12..398e275 100644
--- a/lib/delphi/src/Thrift.Transport.MsxmlHTTP.pas
+++ b/lib/delphi/src/Thrift.Transport.MsxmlHTTP.pas
@@ -106,7 +106,7 @@
   FReadTimeout       := XMLHTTP_SENDRECV_TIMEOUT;
 
   FCustomHeaders := TThriftDictionaryImpl<string,string>.Create;
-  FOutputStream := TThriftStreamAdapterDelphi.Create( TMemoryStream.Create, True);
+  FOutputStream := TThriftStreamAdapterDelphi.Create( TThriftMemoryStream.Create, True);
 end;
 
 function TMsxmlHTTPClientImpl.CreateRequest: IXMLHTTPRequest;
@@ -202,7 +202,7 @@
 
 procedure TMsxmlHTTPClientImpl.Open;
 begin
-  FOutputStream := TThriftStreamAdapterDelphi.Create( TMemoryStream.Create, True);
+  FOutputStream := TThriftStreamAdapterDelphi.Create( TThriftMemoryStream.Create, True);
 end;
 
 procedure TMsxmlHTTPClientImpl.Close;
@@ -217,7 +217,7 @@
     SendRequest;
   finally
     FOutputStream := nil;
-    FOutputStream := TThriftStreamAdapterDelphi.Create( TMemoryStream.Create, True);
+    FOutputStream := TThriftStreamAdapterDelphi.Create( TThriftMemoryStream.Create, True);
     ASSERT( FOutputStream <> nil);
   end;
 end;
@@ -239,13 +239,13 @@
 procedure TMsxmlHTTPClientImpl.SendRequest;
 var
   xmlhttp : IXMLHTTPRequest;
-  ms : TMemoryStream;
+  ms : TThriftMemoryStream;
   a : TBytes;
   len : Integer;
 begin
   xmlhttp := CreateRequest;
 
-  ms := TMemoryStream.Create;
+  ms := TThriftMemoryStream.Create;
   try
     a := FOutputStream.ToArray;
     len := Length(a);
diff --git a/lib/delphi/src/Thrift.Transport.WinHTTP.pas b/lib/delphi/src/Thrift.Transport.WinHTTP.pas
index b0f32ef..746611d 100644
--- a/lib/delphi/src/Thrift.Transport.WinHTTP.pas
+++ b/lib/delphi/src/Thrift.Transport.WinHTTP.pas
@@ -41,7 +41,7 @@
   strict private
     FUri : string;
     FInputStream : IThriftStream;
-    FOutputMemoryStream : TMemoryStream;
+    FOutputMemoryStream : TThriftMemoryStream;
     FDnsResolveTimeout : Integer;
     FConnectionTimeout : Integer;
     FSendTimeout : Integer;
@@ -127,7 +127,7 @@
   FSecureProtocols := DEFAULT_THRIFT_SECUREPROTOCOLS;
 
   FCustomHeaders := TThriftDictionaryImpl<string,string>.Create;
-  FOutputMemoryStream := TMemoryStream.Create;
+  FOutputMemoryStream := TThriftMemoryStream.Create;
 end;
 
 destructor TWinHTTPClientImpl.Destroy;
@@ -269,7 +269,7 @@
 procedure TWinHTTPClientImpl.Open;
 begin
   FreeAndNil( FOutputMemoryStream);
-  FOutputMemoryStream := TMemoryStream.Create;
+  FOutputMemoryStream := TThriftMemoryStream.Create;
 end;
 
 procedure TWinHTTPClientImpl.Close;
@@ -284,7 +284,7 @@
     SendRequest;
   finally
     FreeAndNil( FOutputMemoryStream);
-    FOutputMemoryStream := TMemoryStream.Create;
+    FOutputMemoryStream := TThriftMemoryStream.Create;
     ASSERT( FOutputMemoryStream <> nil);
   end;
 end;
diff --git a/lib/delphi/src/Thrift.Transport.pas b/lib/delphi/src/Thrift.Transport.pas
index 79fc977..558b65e 100644
--- a/lib/delphi/src/Thrift.Transport.pas
+++ b/lib/delphi/src/Thrift.Transport.pas
@@ -334,8 +334,8 @@
   strict private
     FStream : IThriftStream;
     FBufSize : Integer;
-    FReadBuffer : TMemoryStream;
-    FWriteBuffer : TMemoryStream;
+    FReadBuffer : TThriftMemoryStream;
+    FWriteBuffer : TThriftMemoryStream;
   strict protected
     procedure Write( const pBuf : Pointer; offset: Integer; count: Integer); override;
     function Read( const pBuf : Pointer; const buflen : Integer; offset: Integer; count: Integer): Integer; override;
@@ -450,8 +450,8 @@
   strict protected type
     TFramedHeader = Int32;
   strict protected
-    FWriteBuffer : TMemoryStream;
-    FReadBuffer : TMemoryStream;
+    FWriteBuffer : TThriftMemoryStream;
+    FReadBuffer : TThriftMemoryStream;
 
     procedure InitWriteBuffer;
     procedure ReadFrame;
@@ -1053,8 +1053,8 @@
   inherited Create;
   FStream := aStream;
   FBufSize := aBufSize;
-  FReadBuffer := TMemoryStream.Create;
-  FWriteBuffer := TMemoryStream.Create;
+  FReadBuffer := TThriftMemoryStream.Create(FBufSize);
+  FWriteBuffer := TThriftMemoryStream.Create(FBufSize);
 end;
 
 destructor TBufferedStreamImpl.Destroy;
@@ -1379,16 +1379,11 @@
   Result := InnerTransport.IsOpen;
 end;
 
-type
-  TAccessMemoryStream = class(TMemoryStream)
-  end;
-
 procedure TFramedTransportImpl.InitWriteBuffer;
 const DUMMY_HEADER : TFramedHeader = 0;
 begin
   FreeAndNil( FWriteBuffer);
-  FWriteBuffer := TMemoryStream.Create;
-  TAccessMemoryStream(FWriteBuffer).Capacity := 1024;
+  FWriteBuffer := TThriftMemoryStream.Create(1024);
   FWriteBuffer.Write( DUMMY_HEADER, SizeOf(DUMMY_HEADER));
 end;
 
@@ -1448,7 +1443,7 @@
   InnerTransport.ReadAll( buff, 0, size );
 
   FreeAndNil( FReadBuffer);
-  FReadBuffer := TMemoryStream.Create;
+  FReadBuffer := TThriftMemoryStream.Create(1024);
   if Length(buff) > 0
   then FReadBuffer.Write( Pointer(@buff[0])^, size );
   FReadBuffer.Position := 0;