What is the fastest way to export dataGridView rows to Excel or into an SQL Server database

This may be faster way,

    using Excel = Microsoft.Office.Interop.Excel;

    public static void SaveGridToExcel(DataGridView DGV)
    {

        if (DGV.Rows.Count > 0)
        {
            string filename = "";
            SaveFileDialog SV = new SaveFileDialog();
            SV.Filter = "EXCEL FILES|*.xlsx;*.xls";
            DialogResult result = SV.ShowDialog();


            if (result == DialogResult.OK)
            {

                filename = SV.FileName;
                bool multiselect = DGV.MultiSelect;
                DGV.MultiSelect = true;
                DGV.SelectAll();
                DGV.ClipboardCopyMode = DataGridViewClipboardCopyMode.EnableAlwaysIncludeHeaderText;
                Clipboard.SetDataObject(DGV.GetClipboardContent());
                var results = System.Convert.ToString(Clipboard.GetData(DataFormats.Text));
                DGV.ClearSelection();
                DGV.MultiSelect = multiselect;
                Microsoft.Office.Interop.Excel.Application XCELAPP = null;
                Microsoft.Office.Interop.Excel.Workbook XWORKBOOK = null;
                Microsoft.Office.Interop.Excel.Worksheet XSHEET = null;
                object misValue = System.Reflection.Missing.Value;
                XCELAPP = new Excel.Application();
                XWORKBOOK = XCELAPP.Workbooks.Add(misValue);
                XCELAPP.DisplayAlerts = false;
                XCELAPP.Visible = false;
                XSHEET = XWORKBOOK.ActiveSheet;
                XSHEET.Paste();
                XWORKBOOK.SaveAs(filename, Excel.XlFileFormat.xlOpenXMLWorkbook);
                XWORKBOOK.Close(false);
                XCELAPP.Quit();
                try
                {                      
                    System.Runtime.InteropServices.Marshal.ReleaseComObject(XSHEET);
                    System.Runtime.InteropServices.Marshal.ReleaseComObject(XWORKBOOK);
                    System.Runtime.InteropServices.Marshal.ReleaseComObject(XCELAPP);
                }
                catch { }
            }
        }
    }

For me, the best improvement to increase the speed was using this way.

private const string connectionString = "OLEDB;Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=True;Data Source=MYDBSERVER;Use Procedure for Prepare=1;Auto Translate=True;Packet Size=4096;Workstation ID=SERVERID;Use Encryption for Data=False;Tag with column collation when possible=False;Initial Catalog=DBName"; 

object misValue = System.Reflection.Missing.Value;
Excel.Application xlsApp = new Excel.Application();
Excel.Workbook xlsWorkbook = xlsApp.Workbooks.Add(misValue);
Excel.Worksheet myWS = xlsWorkbook.Sheets[1];

 Excel.ListObject lo = myWS.ListObjects.AddEx(Excel.XlListObjectSourceType.xlSrcQuery, connectionString, true, 
 Excel.XlYesNoGuess.xlGuess, myWS.Range["A5"]);
 
//A5 is the starting cell

lo.QueryTable.CommandText = "SELECT * FROM TABLE";
lo.Refresh();

I tried DataReader/Datatable with "for" loop (writting each cell) and both were too much slow recovering a query with 5800 rows (and 40 columns). In numbers:

DataReader - 5:16 minutes
This way - 13 seconds