Speeding up Parallel.ForEach iterating through datatable and rendering report

I am attempting to speed up the processing of 5000 rows received from the database, which I then render as a crystal report, export to a byte stream and save in a database table.

Currently I am using parallel.ForEach on a datatable. This uses 40 parallel processes that then sequentially iterates 125 (i.e 5000/40) records each of the 5000 rows.

It take approximately 5 minutes to do 5000 records at the moment. Is there any way I can speed this up?

DataTable dtBills = new DataTable("dtBills");//I used an OdbcDataAdapter to fill this with 5000 records

private void ParallelProcess()
{
    int numbills = 5000;
    int numprocesses = 40;
    int numsequential = numbills / numprocesses;

    int p=0;

    if (numbills < numprocesses)
        p = numbills;
    else
        p = numprocesses;

    Parallel.For(1, p+1, new ParallelOptions { MaxDegreeOfParallelism = 40 }, i =>
        {
            SequentialProcess(numsequential,i);

        });

}

private void SequentialProcess(int batch,int num)
{
    ReportDocument cryRpt = new ReportDocument();
    cryRpt.Load(Application.StartupPath + "\\" + "Bill.rpt");

    foreach(DataRow drow in dtBills.Rows.Cast<System.Data.DataRow>().Skip((num - 1) * batch).Take(batch).CopyToDataTable().Rows)

    {

        cryRpt.SetParameterValue(..... //here I set Crystal report Parameter values

        Stream stream = cryRpt.ExportToStream(CrystalDecisions.Shared.ExportFormatType.PortableDocFormat);
        byte[] contents = new byte[stream.Length];
        stream.Read(contents, 0, (int)stream.Length);
        stream.Close();

        if (!string.IsNullOrEmpty(sconnstr))
        {
            using (SqlConnection sconn = new SqlConnection(sconnstr))
            {

                String qry = @"INSERT INTO ....."
                using (SqlCommand cmd = new SqlCommand(qry, sconn))
                {

                    cmd.CommandType = CommandType.Text;

                    cmd.Parameters.AddWithValue(// Set values for insert here one of which will be contents

                    cmd.Connection = sconn;

                    sconn.Open();
                    cmd.ExecuteNonQuery();
                    sconn.Close();

                }


            }
        }

    }

    cryRpt.Close();
    cryRpt.Dispose();

}