Memory Issues with Worksheets - epplus

Question

I am seeing what I perceive to be excessive memory use when attempting to get the names of all of the worksheets in a workbook. As soon as I try and open the worksheets inside of the package (excelPackage.Workbook.Worksheets) my test uses ~ 400 MB of memory and takes around 20 seconds to finish that line of code. I am wondering if this is a normal amount of load for the tool to be using for a 30 MB .xlsx file with 3 worksheets. My larger issue is that the tool seems to be keeping around 1.2 GB of memory even after I am done with this ListWorksheets task. So a) 1.2 GB seems excessive for a 30 MB file and b) the memory should be deallocated when the tool is done with it should it not?
Memory plot
[TestMethod]
public void WorkBook_OpenAndCloseWorkBook_MemoryBehavesCorrectly()
{
var template = Path.Combine(testDocumentsRootDirectory, #"Templates\30MB_File.xlsx");
var outputSmokeTest = Path.Combine(testDocumentsRootDirectory, #"Results\MemTest.xlsx");
for (int x = 20; x > 0; x--)
{
smokeTestWorkbook = new Workbook(key);
if (File.Exists(outputSmokeTest))
File.Delete(outputSmokeTest);
smokeTestWorkbook.Open(template);
var worksheets = smokeTestWorkbook.ListWorksheets();
smokeTestWorkbook.SaveAs(outputSmokeTest);
smokeTestWorkbook.Close();
//GC.Collect();
System.Threading.Thread.Sleep(5000);
}
}
/// <summary>
/// Opens a reference to the workbook
/// </summary>
/// <returns></returns>
public void Open(string workbookPath)
{
var loggerString = "Open";
if (File.Exists(workbookPath))
{
try
{
logger.Track(loggerString);
excelPackage = new ExcelPackage(new FileInfo(workbookPath));
}
catch (Exception ex)
{
logger.TrackException(loggerString, ex);
}
}
}
/// <summary>
/// Obtain an array of worksheet names
/// </summary>
/// <returns></returns>
public string[] ListWorksheets()
{
var returnValue = new List<string>();
var loggerString = "ListWorksheets";
try
{
logger.Track(loggerString);
returnValue.AddRange(excelPackage.Workbook.Worksheets.Select(excelWorksheet => excelWorksheet.Name));
}
catch (Exception ex)
{
logger.TrackException(loggerString, ex);
throw;
}
return returnValue.ToArray();
}
/// <summary>
/// SaveAs document
/// </summary>
/// <param name="filename"></param>
/// <returns></returns>
public void SaveAs(string filename)
{
var loggerString = "SaveAs";
try
{
logger.Track(loggerString);
excelPackage.SaveAs(new FileInfo(filename));
}
catch (Exception ex)
{
logger.TrackException(loggerString, ex);
throw;
}
}
/// <summary>
/// Closes the document
/// </summary>
/// <returns></returns>
public void Close()
{
var loggerString = "Close";
try
{
logger.Track(loggerString);
excelPackage.Dispose();
}
catch (Exception ex)
{
logger.TrackException(loggerString, ex);
throw;
}
}