Any ideas on why a 3rd party ODBC driver would run a query super slow from WCF service and super fast from normal console app?

I have a call to a 3rd party ODBC driver as follows:

var DbConnection = new OdbcConnection(@"DSN=QuickBooks Data;SERVER=QODBC;OptimizerDBFolder=%UserProfile%\QODBC Driver for QuickBooks\Optimizer;OptimizerAllowDirtyReads=N;SyncFromOtherTables=Y;IAppReadOnly=Y");
var tb = new DataTable();
using (var ad = new OdbcDataAdapter("SELECT * FROM Customer", DbConnection))
{
   ad.Fill(tb);
}

It runs from a colsole application fine, takes a few seconds.

But if I change nothing else but run it from a self hosted WCF service like this:

[ServiceContract]
public interface IQuickBooksService
{
    [OperationContract]
    DataTable GetQuickBooksData(string query);
}

public class QuickBooksService : IQuickBooksService
{
    public DataTable GetQuickBooksData(string query)
    {
        var DbConnection = new OdbcConnection(@"DSN=QuickBooks Data;SERVER=QODBC;OptimizerDBFolder=%UserProfile%\QODBC Driver for QuickBooks\Optimizer;OptimizerAllowDirtyReads=N;SyncFromOtherTables=Y;IAppReadOnly=Y");
        var tb = new DataTab开发者_StackOverflow社区le();
        using (var ad = new OdbcDataAdapter("SELECT * FROM Customer", DbConnection))
        {
            ad.Fill(tb);
        }
        return tb;
    }
}

I can see the driver working via a status panel it provides but at a pathetic snail pace.

I'm kind of stumped. Any help is appreciated.

Note: the way I'm going to get around this if I don't solve it is to use the database as a message queue and make the (fast) console app poll for messages and put results back into the database (maybe a temp table, I don't know) by dumping the datatable out to XML.

Perhaps due to the reason you serrialize DataTable that contains much data? If you need to poll database through WCF I would use something lighter than DataTable and consider asynch operations