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我用于生成 Excel 电子表格的混合 Excel Interop/EPPlus 应用程序在每次执行时运行速度逐渐变慢。

为了找出原因，我下载了 ANTS Memory Profiler 并运行了该应用程序。

ANTS MP 在其“加载到 CLR 中的程序集”详细信息中告诉我有 2 个动态生成的程序集。一个是在“InitializeExcelObjects()”方法中，这是有道理的，因为它创建了一个 Excel.Application 和相关对象。但是（据说？）加载程序集的第二种方法是：

private void WriteHeader(String shortName)
{
    const int LOGO_FIRST_ROW = 1;
    const int LOGO_LAST_ROW = 5;
    var rowRngUnitName = _xlSheet.Range[_xlSheet.Cells[UNIT_NAME_ROW, 1], _xlSheet.Cells[UNIT_NAME_ROW, 3]];
    rowRngUnitName.Merge(Type.Missing);
    rowRngUnitName.Font.Bold = true;
    rowRngUnitName.Font.Size = UNIT_NAME_FONT_SIZE;
    rowRngUnitName.Value2 = shortName;

    var rowRngRptTitle = _xlSheet.Range[_xlSheet.Cells[REPORT_TITLE_ROW, 1], _xlSheet.Cells[REPORT_TITLE_ROW, 5]];
    rowRngRptTitle.Merge(Type.Missing);
    rowRngRptTitle.Font.Size = REPORT_TITLE_ROW_FONT_SIZE;
    rowRngRptTitle.Font.Bold = true;
    rowRngRptTitle.Value2 = ProduceUsageByMonthLabel;

    var rowRngRptAdvisory = _xlSheet.Range[_xlSheet.Cells[REPORT_ADVISORY_ROW, 1], _xlSheet.Cells[REPORT_ADVISORY_ROW, 4]];
    rowRngRptAdvisory.Merge(Type.Missing);
    rowRngRptAdvisory.Font.Size = REPORT_ADVISORY_ROW_FONT_SIZE;
    rowRngRptAdvisory.Value2 = ProductsHiddenAdvisoryLabel;

    // col 5A (ANNUAL_CONTRACT_PRODUCTS_ROW)
    var rowRngContractProducts = _xlSheet.Range[
        _xlSheet.Cells[ANNUAL_CONTRACT_PRODUCTS_ROW, ITEMDESC_COL],
        _xlSheet.Cells[ANNUAL_CONTRACT_PRODUCTS_ROW, ITEMDESC_COL]];
    rowRngContractProducts.Merge(Type.Missing);
    rowRngContractProducts.Font.Size = ANNUAL_CONTRACT_PRODUCTS_LEGEND_FONT_SIZE;
    rowRngContractProducts.Font.Bold = true;
    rowRngContractProducts.HorizontalAlignment = XlHAlign.xlHAlignCenter;
    rowRngContractProducts.VerticalAlignment = XlVAlign.xlVAlignCenter;
    rowRngContractProducts.Value2 = AnnualContractProductsLabel;
    Borders border = rowRngContractProducts.Borders;
    border.Weight = XlBorderWeight.xlThin;
    border.LineStyle = XlLineStyle.xlContinuous;

    // Logo
    var logoRange = _xlSheet.Range[
        _xlSheet.Cells[LOGO_FIRST_ROW, _grandTotalsColumn], _xlSheet.Cells[LOGO_LAST_ROW, _grandTotalsColumn + 1]];
    ReportRunnerConstsAndUtils.PlacePicture(_logo, logoRange);
}

...牵连的是这个：

var rowRngUnitName = _xlSheet.Range[_xlSheet.Cells[UNIT_NAME_ROW, 1], _xlSheet.Cells[UNIT_NAME_ROW, 3]];

...它没有做任何不寻常的事情（范围在代码中的所有位置都分配了，那么为什么这个被认为与其他不同并且是程序集的产生者）？

是因为这是第一次分配范围吗？完成后是否会动态加载某些程序集（仅一次）？

这是调用相关方法的代码：

public bool GenerateProduceUsageRpt()
{
    const int SLEEPY_TIME = 10000;
    const int MONTH_SPLIT_CUTOFF = 7;
    try
    {
        InitializeExcelObjects();
        _monthsInReport = ReportRunnerConstsAndUtils.GetMonthsInReport(_monthBegin, _monthEnd, _beginYearStr, _endYearStr);
        _grandTotalsColumn = _monthsInReport + 3;
        _grandTotalsColumnPivotTable = _grandTotalsColumn - 1;

        _lastMonthColumn = _grandTotalsColumn - 1;

        InitializeYearAndMonthVals();

        try
        {
            System.Windows.Forms.Application.DoEvents();
            if (_xlSheet != null)
            {
                _xlSheet.Name = ProduceUsageByMonthSheetName;
                _xlPivotDataSheet.Name = ProduceUsageByMonthPivotTableSheetName;
                _xlPivotTableSheet.Name = "PivotTable";

                WriteHeader(_unit);
                WriteColumnHeadings();
                . . .

这是意料之中的（因为此时程序集是动态加载的），或者这可能与正在经历的逐渐恶化的性能有关？

更新

根据 Glenn Ferrie 的评论，这种方法可能很有趣：

// From Jürgen Tschandl at http://stackoverflow.com/questions/7413107/excel-image-in-a-cell
internal static void PlacePicture(Image picture, Range destination)
{
    Worksheet ws = destination.Worksheet;
    Clipboard.SetImage(picture);
    ws.Paste(destination, false);
    Pictures p = ws.Pictures(Missing.Value) as Pictures;
    if (p != null)
    {
        Picture pic = p.Item(p.Count) as Picture;
        ScalePicture(pic, (double)destination.Width, (double)destination.Height);
    }
}
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