Problem to slow process

                var ExcelObj = new Excel.Application();
                //Excel.Workbook Book0 = ExcelObj.Workbooks.Open(openFileDialog1.FileName, 0, false, 5, "", "", true, Excel.XlPlatform.xlWindows, "\t", false, false, 0, true);
                ExcelObj.ScreenUpdating = false;

                Excel.Worksheet Worksheet0;
                string Folder0 = Path.GetDirectoryName(openFileDialog1.FileName);
                string Path0 = Folder0 + "\\New0.xlsx";
                string Col0 = "", Row0 = "";

                using (FileStream fs = new FileStream(openFileDialog1.FileName, FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite))
                {
                    using (SpreadsheetDocument doc = SpreadsheetDocument.Open(fs, true))
                    {
                        WorkbookPart workbookPart = doc.WorkbookPart;

                        /*Sheet theSheet = workbookPart.Workbook.Descendants<Sheet>().
                            Where(s => s.Name == "Sheet Overall").FirstOrDefault();*/
                        Sheet theSheet;

                        int sheetIndex = 0;
                        DocumentFormat.OpenXml.Spreadsheet.Sheets sheets = workbookPart.Workbook.Sheets;
                        //foreach (WorksheetPart wsPart in workbookPart.WorksheetParts)
                        foreach (Sheet sheet in sheets)
                        {
                            //WorkbookStylesPart wstylePart = workbookPart.WorkbookStylesPart;
                            //Stylesheet ss = wstylePart.Stylesheet;
                            Boolean b = CreateSpreadsheetWorkbook(Path0, sheet.Name);
                            string sheetPartType = workbookPart.GetPartById(sheet.Id).GetType().Name;
                            using (StreamWriter sw = new StreamWriter(@File1, true, Encoding.Unicode))
                            {
                                sw.WriteLine("Sheet name is {0},Sheet ID is {1},sheetId is {2},sheetPartType is {3}", sheet.Name, sheet.Id, sheet.SheetId, sheetPartType);
                            }

                            if (sheetPartType != "WorksheetPart")
                            {
                                //Console.WriteLine("{0} is not a worksheet", sheet.Name);
                                using (StreamWriter sw = new StreamWriter(@File1, true, Encoding.Unicode))
                                {
                                    sw.WriteLine("{0} is not a worksheet", sheet.Name);
                                }
                            }
                            else
                            {
                                WorksheetPart worksheetPart = (WorksheetPart)workbookPart.GetPartById(sheet.Id);
                                WorkbookStylesPart wstylePart = workbookPart.WorkbookStylesPart;
                                Stylesheet ss = wstylePart.Stylesheet;

                                foreach (Cell cell in worksheetPart.Worksheet.Descendants<Cell>())
                                {
                                    if (cell != null)
                                    {
                                        using (StreamWriter sw = new StreamWriter(@File1, true, Encoding.Unicode))
                                        {
                                            if (cell.DataType == null)
                                            {
                                                sw.WriteLine("Cell reference is {0}; Cell value is {1}", cell.CellReference, cell.InnerText);
                                                Col0 = ColumnPart(cell.CellReference); Row0 = RowPart(cell.CellReference);

                                                InsertText(doc, sheet.Name, cell.InnerText, Col0, Convert.ToUInt32(Row0));
                                            }
                                            else
                                            {
                                                switch (cell.DataType.Value)
                                                {
                                                    case CellValues.SharedString:

                                                        var stringTable =
                                                            workbookPart.GetPartsOfType<SharedStringTablePart>()
                                                            .FirstOrDefault();

                                                        if (stringTable != null)
                                                        {
                                                            sw.WriteLine("Cell reference is {0}; Cell value is {1}", cell.CellReference, stringTable.SharedStringTable.ElementAt(int.Parse(cell.InnerText)).InnerText);
                                                            Col0 = ColumnPart(cell.CellReference); Row0 = RowPart(cell.CellReference);
                                                            InsertText(doc, sheet.Name, cell.InnerText, Col0, Convert.ToUInt32(Row0));
                                                        }
                                                        break;
                                                }
                                            }
                                        }
                                    }
                                    ...
        public static void InsertText(SpreadsheetDocument spreadSheet, string SheetName0, string text, string CellRowRef0, uint CellColRef0)
        {
            //using (SpreadsheetDocument spreadSheet = SpreadsheetDocument.Open(docName, true))
            // Open the document for editing.
            //Using(SpreadsheetDocument spreadSheet = SpreadsheetDocument.Open(docName, true))
            //{
            // Get the SharedStringTablePart. If it does not exist, create a new one.
            SharedStringTablePart shareStringPart;
            if (spreadSheet.WorkbookPart.GetPartsOfType<SharedStringTablePart>().Count() > 0)
            {
                shareStringPart = spreadSheet.WorkbookPart.GetPartsOfType<SharedStringTablePart>().First();
            }
            else
            {
                shareStringPart = spreadSheet.WorkbookPart.AddNewPart<SharedStringTablePart>();
            }

            // Insert the text into the SharedStringTablePart.
            // int index = InsertSharedStringItem(text, shareStringPart);

            // Insert a new worksheet.
            WorksheetPart worksheetPart = InsertWorksheet(spreadSheet.WorkbookPart);

            // Insert cell A1 into the new worksheet.
            Cell cell = InsertCellInWorksheet(CellRowRef0, CellColRef0, worksheetPart);

            // Set the value of cell A1.
            cell.CellValue = new CellValue(text);
            cell.DataType = new EnumValue<CellValues>(CellValues.SharedString);

            // Save the new worksheet.
            worksheetPart.Worksheet.Save();
            //}
        }

        // Given a column name, a row index, and a WorksheetPart, inserts a cell into the worksheet.
        // If the cell already exists, returns it.
        private static Cell InsertCellInWorksheet(string columnName, uint rowIndex, WorksheetPart worksheetPart)
        {
            DocumentFormat.OpenXml.Spreadsheet.Worksheet worksheet = worksheetPart.Worksheet;
            SheetData sheetData = worksheet.GetFirstChild<SheetData>();
            string cellReference = columnName + rowIndex;

            // If the worksheet does not contain a row with the specified row index, insert one.
            Row row;
            if (sheetData.Elements<Row>().Where(r => r.RowIndex == rowIndex).Count() != 0)
            {
                row = sheetData.Elements<Row>().Where(r => r.RowIndex == rowIndex).First();
            }
            else
            {
                row = new Row() { RowIndex = rowIndex };
                sheetData.Append(row);
            }

            // If there is not a cell with the specified column name, insert one.
            if (row.Elements<Cell>().Where(c => c.CellReference.Value == columnName + rowIndex).Count() > 0)
            {
                return row.Elements<Cell>().Where(c => c.CellReference.Value == cellReference).First();
            }
            else
            {
                // Cells must be in sequential order according to CellReference. Determine where to insert the new cell.
                Cell refCell = null;
                foreach (Cell cell in row.Elements<Cell>())
                {
                    if (string.Compare(cell.CellReference.Value, cellReference, true) > 0)
                    {
                        refCell = cell;
                        break;
                    }
                }

                Cell newCell = new Cell() { CellReference = cellReference };
                row.InsertBefore(newCell, refCell);

                worksheet.Save();
                return newCell;
            }
        }
        // Given text and a SharedStringTablePart, creates a SharedStringItem with the specified text
        // and inserts it into the SharedStringTablePart. If the item already exists, returns its index.
        private static int InsertSharedStringItem(string text, SharedStringTablePart shareStringPart)
        {
            // If the part does not contain a SharedStringTable, create one.
            if (shareStringPart.SharedStringTable == null)
            {
                shareStringPart.SharedStringTable = new SharedStringTable();
            }

            int i = 0;

            // Iterate through all the items in the SharedStringTable. If the text already exists, return its index.
            foreach (SharedStringItem item in shareStringPart.SharedStringTable.Elements<SharedStringItem>())
            {
                if (item.InnerText == text)
                {
                    return i;
                }

                i++;
            }

            // The text does not exist in the part. Create the SharedStringItem and return its index.
            shareStringPart.SharedStringTable.AppendChild(new SharedStringItem(new DocumentFormat.OpenXml.Spreadsheet.Text(text)));
            shareStringPart.SharedStringTable.Save();

            return i;
        }

Many Thanks & Best Regards, Hua Min