powershell - Runtime of Foreach-Object vs Foreach loop

Question

I want to do a progress bar of my script but then I need a total amount of folders.

Is there a significant runtime difference between:

Get-ChildItem $path -Directory | ForEach-Object {
    #do work
}

and

$folders = Get-ChildItem $path -Directory
foreach($folder in $folders){
    #do work
}

Then I can use $folders.Count as my total amount of folders. I don't know how to do it with a foreach-object loop.

Answer 1

Yes, there is a performance difference. foreach is faster than ForEach-Object, but requires more memory, because all items ($folders) must be in memory. ForEach-Object processes one item at a time as they're passed through the pipeline, so it has a smaller memory footprint, but isn't as fast as foreach.

See also.