suspendDirty and resumeDirty

var startTime, endTime;
window.onload = function () 
{
    var spread = new GC.Spread.Sheets.Workbook(document.getElementById("ss"));
    var sheet = spread.getActiveSheet();
    var data = generateData(50000);
    var colInfos = generateBindingColumnInfos(7);
    loadingData(sheet, colInfos, data);
    spread.bind(GC.Spread.Sheets.Events.RangeSorting, function (sneder, args) 
    {
     // Calling suspendDirty() method to stop the marking sorted cells dirty
     sheet.suspendDirty();
    });
    spread.bind(GC.Spread.Sheets.Events.RangeSorted, function (sender, args) 
    {
     // Calling resumeDirty() method to restore dirty status of cells
     sheet.resumeDirty();
    });
};
function loadingData(sheet, colInfos, data)
    {
     sheet.suspendPaint();
     sheet.autoGenerateColumns = false;
     sheet.bindColumns(colInfos);
     sheet.setDataSource(data);
     sheet.rowFilter(new GC.Spread.Sheets.Filter.HideRowFilter(new GC.Spread.Sheets.Range(0, 0, sheet.getRowCount(), sheet.getColumnCount())));
     sheet.resumePaint();
    }
function generateData(itemCount) 
{
     var data = [];
     var countries = ["China", "American", "UK", "Japan", "France"];
     var products = ["Computer", "Car", "Others"];
     var colors = ["Red", "Green", "Blue", "White", "Black", "Yellow", "Pink", "Orange"];
     var dt = new Date();
    for (var i = 0; i < itemCount; i++)
        {
            var item =
            {
             id: i,
             date: new Date(dt.getFullYear(), i % 12, 1),
             country: countries[Math.floor(Math.random() * countries.length)],
             product: products[Math.floor(Math.random() * products.length)],
             color: colors[Math.floor(Math.random() * colors.length)],
             amount: 1000 + Math.random() * 10000,
             big: Math.random() > .5
            };
         data.push(item);
        }
    return data;
}
function generateBindingColumnInfos(colCount) 
{
     var bindColumnInfos = [
     { name: "id", displayName: "ID", size: 60 },
     { name: "product", displayName: "Product", size: 90 },
     { name: "country", displayName: "Country", size: 90 },
     { name: "amount", displayName: "Amount", size: 90, formatter: "#,##0" },
     { name: "date", displayName: "Date", size: 90, formatter: 'yyyy-mm-dd' },
     { name: "color", displayName: "Color", size: 85 },
     { name: "big", displayName: "Big", size: 90, cellType: new GC.Spread.Sheets.CellTypes.CheckBox() }
     ];
   return bindColumnInfos;
}