Powershell and Excel - Datatable slow with too many rows - sql-server

Question

I'm trying to fill an Excel sheet using powershell :
0. Declaring Excel object
$Excel = New-Object -ComObject Excel.Application
$Excel.DisplayAlerts = $false
$Excel.ScreenUpdating = $false
$Excel.DisplayStatusBar = $false
$Excel.EnableEvents = $false
$Excel.Visible = $False
1. Reading data from a database table :
$dt1 = New-Object System.Data.Dataset
2. Getting the table :
$dt_table1 = $dt1.Tables[0]
3. Filling Excel file :
for ([Int]$m = 0; $m -lt $dt_table1.Rows.Count; $m++)
{
for ([Int]$r = 0; $r -lt $dt_table1.Columns.Count; $r++)
{
$incolumn = $r + 1;
$inrow = $inheaderlenght + 2 + $m;
if($incolumn -gt 2)
{
$Workbook.ActiveSheet.Cells.Item($inrow, $incolumn) = [System.Convert]::ToDecimal($dt_table1.Rows[$m].ItemArray[$r])
}
else
{
$Workbook.ActiveSheet.Cells.Item($inrow, $incolumn) = $dt_table1.Rows[$m].ItemArray[$r].ToString()
}
}
}
With a few hundreds of rows the sheet is filling in seconds, the problem is when i got thousands of rows, is very slow, for example to fill 21.500 rows it need 15 min at least.
I'm executing this code in my production server, with 32GB of RAM and an Intel Xeon processor.
I would like to improve the performance, i need to fill an Excel file with 32 sheets and only few sheets have thousands of rows.
UPDATE: I wanted to fill directly an array into the Excel sheet :
$excelArray = New-Object 'object[,]' $dt_table1.Rows.Count, $dt_table1.Columns.Count
$excelArray = ForEach($Row in $dt1.Tables[0].Rows){
$Record = New-Object PSObject
ForEach($Col in $dt1.Tables[0].Columns.ColumnName){
Add-Member -InputObject $Record -NotePropertyName $Col -NotePropertyValue $Row.$Col
}
$Record
}
But now, the next line fails:
$range = $WorkSheet.Range('A1', ([char](64 + $dt_table1.Columns.Count)).ToString() + ($dt_table1.Rows.Count).ToString() )
$range.Value2 = $excelArray

Answer 1

Shamelessly using some of f6a4's answer, I think this could work:
# 3. Filling Excel file :
# convert to array of objects
$tableData = $dt_table1 | Select-Object * -ExcludeProperty ItemArray, Table, RowError, RowState, HasErrors
# select the range in the worksheet
$endRange = '{0}{1}' -f ([char](64 + $dt_table1.Columns.Count)), $dt_table1.Rows.Count
$range = $Workbook.ActiveSheet.Range('A1', $endRange)
# copy the array to excel range
$range.Value2 = $tableData

Answer 2

Ok, now i found solution.
$excelArray | ConvertTo-CSV -NoType -Del "`t" | Select -Skip 1 | Clip
[void]$WorkSheet.columns.Item(1).cells.Item(2).PasteSpecial()
From 15 min to 2 min. This really helps me a lot, i have to produce like 500+ Excel files.