Process a large chunk of data in Web Service. Performance, Performance,Performance

Recently, I met a challenge to pass down a large chunk of data from a ASP.Net Server to Client. The data is structured as an object so serialization won't be a problem. But the data is about couple mb. What I did is to put this object into web response as attachment. The result is web service response time reduce half. I believe the reason behide this is that IIS might be doing some encoding/decoding that kill the performace.
This is what I did:
1: Install Microsoft WSE 2.0
2: When you finishe the web service process and before you return the response back, use the following code to return the response

System.IO.MemoryStream ms = new System.IO.MemoryStream();

System.IO.StreamWriter sw = new System.IO.StreamWriter(ms);

XmlSerializer serializer = null;

serializer = new XmlSerializer(typeof(MyObject), "http://MYObjectService/Service.asmx/20040803");

serializer.Serialize(sw, ret);

sw.Flush();

ms.Position = 0;

SoapContext respContext = ResponseSoapContext.Current;

DimeAttachment attachment = new DimeAttachment("text/plain",

TypeFormat.MediaType,

ms);

respContext.Attachments.Add(attachment);

serializer = null;

return "OK";

That will do it.

BTW: In order to extract the attachment at the client side, you need to install the WSE as well and use the response context object to extract the entire responese out.