I would take things outside of the “aspx” pipeline. In particular, I would write a ran handler (ashx, or mapped via config), that does the minimum work, and simply writes to the response in chunks. The handler would accept input from the query-string/form as normal, locate the object to stream, and stream the data (using a moderately sized local buffer in a loop). A simple (incomplete) example shown below:
public void ProcessRequest(HttpContext context) {
// read input etx
context.Response.Buffer = false;
context.Response.ContentType = "text/plain";
string path = @"c:\somefile.txt";
FileInfo file = new FileInfo(path);
int len = (int)file.Length, bytes;
context.Response.AppendHeader("content-length", len.ToString());
byte[] buffer = new byte[1024];
Stream outStream = context.Response.OutputStream;
using(Stream stream = File.OpenRead(path)) {
while (len > 0 && (bytes =
stream.Read(buffer, 0, buffer.Length)) > 0)
{
outStream.Write(buffer, 0, bytes);
len -= bytes;
}
}
}