Sets the calculation mode, this setting will only affect I/O of MS Excel/SSJSON/SJS files. Setting CalculationMode as CalculationMode.Manual will prevent MS Excel or SpreadJS from automatically calculating formulas on opening the workbook.Additionally, CalculationMode.Manual improves the speed of opening workbooks that contain a large number of formulas in MS Excel and SpreadJS.If you want to disable the calculation for the current workbook, please use Workbook.setEnableCalculation(boolean).