Iterating through a spreadsheet (Too slow!)

Hey everyone. I'm very new to power shell and have written a script to iterate through a spreadsheet, removing duplicate email addresses from another multiple sheet workbook.

It works, but is very slow.

Can I fix this by using a function and "exit"? if so, how do I pass arguments into a function with powershell?

Thanks

P.S. not yet sure how to apply the code tags on this site....

(Please visit the site to view this media)

# Ray Winkelman 2014 © All Rights Reserved.
# This script iterates through an excel spreadsheet
 param($Work)

# restart PowerShell with -noexit, the same script, and 1
 if (!$Work) {
     powershell -noexit -file $MyInvocation.MyCommand.Path 1
     return
 }

$strMailListPath = "C:\Mailer\MailingList.xls"
$strUnsubscribeListPath = "C:\Users\Doug\Desktop\Unsubscribers\UnsubscribeList.xls"

$objExcel = New-Object -comobject Excel.Application
$objExcel.Visible = $false
$objExcel.DisplayAlerts = $false
$objWorkbook = $objExcel.Workbooks.Open($strMailListPath)
$objWorkbookUns = $objExcel.Workbooks.Open($strUnsubscribeListPath)

write-host "Parsing Unsubscribe List."

$UnsRow = 1
$UnsSheet = 1
  
$row = 1
$sheet = 1


$objSheetUns = $objWorkbookUns.Sheets.Item($UnsSheet)
write-Host "Unsubscribe Worksheet: " $objSheetUns.Name


#Iterating through the -- UNS -- rows, stopping at the first blank in col 1
while ($objSheetUns.Cells.Item($UnsRow,1).Text -ne "")
{
            write-Host "Checking For Unsubscriber: " $objSheetUns.Cells.Item($UnsRow,1).Text
           
            while ($sheet -le $objWorkbook.Sheets.Count)
            {
              $objSheet = $objWorkbook.Sheets.Item($sheet)

              #Iterating through the rows, stopping at the first blank in col 1
              while ($objSheet.Cells.Item($row,1).Text -ne "")
              {  
                   if ($objSheetUns.Cells.Item($UnsRow,1).Text -eq $objSheet.Cells.Item($row,1).Text)
                   {
                            $range = $objSheet.Cells.Item($row, 1).EntireRow
                            $range.Interior.ColorIndex = 3
                            write-Host "Found: " $objSheetUns.Cells.Item($UnsRow,1).Text " In: " $objSheetUns.Name
                            write-Host "---"
                   }
            
                $row += 1
              }

              $sheet += 1
              $row = 1
            }
        
$UnsRow += 1
$sheet = 1
}

Start-Sleep 5
$objWorkbookUns.Close()
$objWorkbook.SaveAs("C:\Mailer\MailingList.xls")
$objWorkbook.Close()
$objExcel.Quit()
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($objExcel)
Remove-Variable objExcel