List Iteration Taking So Much Time?

I have List (of class). having 1800 of count and each object has 90 properties. When I terate earch with 90 properties taking more and more time. How to resolve this

Dim cellIntStyle As HSSFCellStyle = hssfworkbook.CreateCellStyle
cellIntStyle.DataFormat = HSSFDataFormat.GetBuiltinFormat("#")
Dim cellDateStyle As HSSFCellStyle = hssfworkbook.CreateCellStyle
cellDateStyle.DataFormat = HSSFDataFormat.GetBuiltinFormat(Format
("dd-MMM-yyyy"))
For Each mReport As Report In dtExcel
row = sheet1.CreateRow(iRow)
j = 0
For Each prop As PropertyInfo In props
Dim value As Object = prop.GetValue(mReport, Nothing)
If IsInt(value) Then
CreateRow(row, j, CType(value, Integer), cellIntStyle)
ElseIf IsDate(value) Then
CreateRow(row, j, String.Format("{0:dd-MMM-yyyy}",
value), cellDateStyle)
Else
CreateRow(row, j, value)
End If
j = j + 1
Next
iRow = iRow + 1 // Coming here taking so long... how to make it fast.
Next
Private Sub CreateRow(ByRef row As HSSFRow, ByVal colId As Integer,
ByVal value As String)
row.CreateCell(colId).SetCellValue(value)
End Sub
Private Sub CreateRow(ByRef row As HSSFRow, ByVal colId As Integer,
ByVal value As Integer,
ByVal cellStyle As HSSFCellStyle)
Dim cell As HSSFCell = row.CreateCell(colId)
cell.SetCellValue(value)
cell.CellStyle = cellStyle
End Sub
Private Sub CreateRow(ByRef row As HSSFRow, ByVal colId As Integer,
ByVal value As String,
ByVal cellStyle As HSSFCellStyle)
Dim cell As HSSFCell = row.CreateCell(colId)
cell.SetCellValue(value)
cell.CellStyle = cellStyle
End Sub