list vs arr

list-vs-arr.ps1

$arr  = 1..100
$repe = 1..100
Measure-Command { 
    foreach ($i in $repe) {
        $l = New-Object 'System.Collections.Generic.List[Object]'
        foreach ($ii in $arr) {
            $l.Add($ii)
        }
    }
    $l.count -eq $arr.count
}

Measure-Command { 
    foreach ($i in $repe) {
        $l = @()
        foreach ($ii in $arr) {
            $l += $ii
        }
    }
    $l.count -eq $arr.count
}

New-Object <- super slow, [System.Collections.Generic.List[Object]]@() (v3+) or [System.Collections.Generic.List[Object]]::new() (v5+) is the way to go.