Get N most recent (or by any other value function) files without sorting entire list.

recentmost-example.ps1

function InsertSorted($array, $item, $maxn, [scriptblock]$valueFunction) {
    $a = $valueFunction.InvokeReturnAsIs($item);
    $j = for($i = 0; $i -lt $array.Count; $i++) {
        $b = $valueFunction.InvokeReturnAsIs($array[$i]);
        if ($a -lt $b) { $i; break }
    }
    if($j -eq $null) {
        return ($array[0..($array.Count-1)] + $item)[-$maxn..-1];
    } elseif($j -eq 0) {
        if($array.Count -lt $maxn) {
            return (@() + $item + $array[0..($array.Count-1)]);
        } else {
            return $array;
        }
    } else {
        return ($array[0..($j-1)] + $item + $array[($j)..($array.Count-1)])[-$maxn..-1];
    }
}

function Get-MaxN{
    [CmdletBinding()]
    param (
        [Parameter(Mandatory=$true, ValueFromPipeline=$true)][PSObject[]]$InputObject,
        [Parameter(Mandatory=$true)][scriptblock]$ValueFunction,
        [Parameter(Mandatory=$true)][int]$N
    )
    $selected = @();
    $Input | foreach {
        if($selected.Count -eq 0) {
            $selected = ,$_;
        } else {
            $selected = InsertSorted $selected $_ $N $ValueFunction;
        }
    }
    return $selected;
}

function Get-LastWriteTime([System.IO.FileSystemInfo]$item) {
    return $item.LastWriteTime;
}

gci . -file | Get-MaxN -ValueFunction ${function:Get-LastWriteTime} -N 5