Why does the datacontract serialization run out of memory?

I have created a new SL 5 Web Site Application. I made all the contract stuff and can call the service and return to the client successfully. And I have a bunch of the config parameters set to their maxes so that I can return a large list of objects (approx. 80k of them).

The first time I run it in the debugger and call the service method, everything is good.  The second time and all subsequent times until I restart VS, they fail on serialization in the service.  Why can it work once and not another time?

Here is my code (in Oxygene language):

   method ViewModel.GetSurveyHeaders: List<VSDS.Data.DataContracts.SurveyHeader>;
      begin

      SurveyHeaders := nil;

      var Proxy := ServiceProxy.NewClient;
      Proxy.GetSurveyHeadersCompleted += ProxyGetSurveyHeadersCompleted;
      Proxy.GetSurveyHeadersAsync;
      end;

   method ViewModel.ProxyGetSurveyHeadersCompleted(sender: Object; e: GetSurveyHeadersCompletedEventArgs);
      begin
      if sender <> nil then begin
         VSDSRestServiceClient( sender ).GetSurveyHeadersCompleted -= ProxyGetSurveyHeadersCompleted;
         VSDSRestServiceClient( sender ).CloseAsync;
         end;

      if e.Error <> nil then begin
         MessageBox.Show( 'Error: ' + e.Error.Message  );
         exit;
         end;

      self.SurveyHeaders := e.Result;

      end;

It is acting like the server is caching the original requested data and not giving up the memory when it is done serializing.

Anybody got a clue?   (no, I'm not going to change the amount of data I'm returning.  not an option)