Question

Why is it that writing cell values to Excel is a lot faster in VBScript than in PowerShell?
Isn’t PowerShell the new thing, and VBScript the deprecated MS scripting language?

VBScript example (save to filename.vbs)
This runs in a split second.

Set objExcel = CreateObject("Excel.Application")
objExcel.Visible = false
Set objWorkbook = objExcel.Workbooks.Add()

' Edit: increased number of writes to 500 to make speed difference more noticeable
For row = 1 To 500
     'Edit: using .cells(row,1) instead of .cells(50,1) - this was a mistake
     objWorkbook.workSheets(1).cells(row,1).value = "test"
Next

objWorkbook.SaveAs(CreateObject("Scripting.FileSystemObject").GetParentFolderName(WScript.ScriptFullName) & "\test.xlsx")
objExcel.Quit
msgbox "Done."

PowerShell example (save to filename.ps1) This takes multiple seconds to run (problematic on thousands of records)

#need this to work around bug if you use a non-US locale: http://support.microsoft.com/default.aspx?scid=kb;en-us;320369
[System.Threading.Thread]::CurrentThread.CurrentCulture = "en-US" 

$excel = New-Object -ComObject Excel.Application
$excel.Visible = $False
$xls_workbook = $excel.Workbooks.Add()

# Edit: using foreach instead of for
# Edit: increased number of writes to 500 to make speed difference more noticeable
foreach ($row in 1..500) {
    # Edit: Commented out print-line, slows down the script
    #"Row " + $row
    # This is very slow! - http://forums.redmondmag.com/forums/forum_posts.asp?tid=4037&pn=7
    $xls_workbook.sheets.item(1).cells.item($row,1) = "test"
}

$xls_workbook.SaveAs($MyInvocation.MyCommand.Definition.Replace($MyInvocation.MyCommand.Name, "") + "test.xlsx")
$excel.Quit()
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($excel)

I want to use this for thousands of records. If there is no fast way to do this, PowerShell is not an option. Are there better alternatives?

Answer 1

You can speed things up by not looping through individual cells:

$excel = New-Object -ComObject Excel.Application
$excel.Visible = $True
$xls_workbook = $excel.Workbooks.Add()

$range = $xls_workbook.sheets.item(1).Range("A1:A100")
$range.Value2 = "test"

If you want to write an array of values to a range, here is a nice blog post that demonstrates similar technique:

How to Get Data into an Excel Spreadsheet Very Quickly with PowerShell