Powershell grinds to a halt part way through processing - excel

Question

I have the following power-shell (4.0) script. It opens an excel book (2013) and gets a url from a cell and opens it. It then downloads the web page to a .htm file. It iterates through each row in the worksheet (~3000).
The problem I am having is the first ~500 files are done in about 3 minutes. It then appears to slow down considerably to where only one file is created every 2-3 minutes. I have checked my available ram and cpu usage and both are fine (ram 2.93gb used of 8gb, cpu is at 35%).
Is there anything I can do to get round this and speed it up?
cls
$output_folder = "c:\temp"
$OUTPUT_FILENAME=""
# comment following line to add a timestamp to each file gets created
if($OUTPUT_FILENAME.length -eq 0) {$OUTPUT_FILENAME=(get-date).tostring().replace(" ","").replace("/","").replace(":","")}
$filepath = "C:\Temp\MeteringHistory\Meters for Maximo Upload"
$xl = New-Object -COM "Excel.Application"
$xl.Visible = $false
$wb = $xl.Workbooks.Open($filepath)
$ws = $wb.Worksheets.Item("WOhistory")
$maxRow = ($ws.UsedRange.rows).count
$minRow = 1
for ($minrow -le $maxrow ; $minrow++)
{
$website = $ws.cells.item($minRow, 1).text
$fileName = $ws.cells.item($minRow, 5).text + " - " + $ws.cells.item($minRow, 4).text
$fileName = $fileName -replace '/', '_'
$wc=new-object system.net.webclient
$wc.UseDefaultCredentials = $true
$wc.downloadfile($website,"c:\temp\MeteringHistory\Files\$filename.htm")
$wc.Dispose()
}

Answer 1

I would export Excel to CSV first and ditch Excel afterwards. You can even do this from powershell itself. Then use invoke-webrequest instead of all that boilerplate you had and be done with it. It can be done in only couple of lines of code. That way you reduce the issue to the basic powershell.
Too speed up this process you could then invoke-webrequest in parallel via background jobs.

Answer 2

Hard to know what's wrong without an error. I would try one thing though: Avoid creating and disposing hundreds of WebClient-objects when you can reuse the first one. Try:
cls
$output_folder = "c:\temp"
$OUTPUT_FILENAME=""
# comment following line to add a timestamp to each file gets created
if($OUTPUT_FILENAME.length -eq 0) {$OUTPUT_FILENAME=(get-date).tostring().replace(" ","").replace("/","").replace(":","")}
$filepath = "C:\Temp\MeteringHistory\Meters for Maximo Upload"
$xl = New-Object -COM "Excel.Application"
$xl.Visible = $false
$wb = $xl.Workbooks.Open($filepath)
$ws = $wb.Worksheets.Item("WOhistory")
$maxRow = ($ws.UsedRange.rows).count
$minRow = 1
$wc=new-object system.net.webclient
$wc.UseDefaultCredentials = $true
for ($minrow -le $maxrow ; $minrow++) {
$website = $ws.cells.item($minRow, 1).text
$fileName = $ws.cells.item($minRow, 5).text + " - " + $ws.cells.item($minRow, 4).text
$fileName = $fileName -replace '/', '_'
$wc.DownloadFile($website,"c:\temp\MeteringHistory\Files\$filename.htm")
}
$wc.Dispose()