PowerShell Transpose Objects und Memoryleak

$xmlEvent = @(); $xmlEvents = @();
$filter = @{
    Logname   = "Security";  
    ID        = 4624;
    StartTime = (Get-Date).AddDays(-10);
}
$filterSid = "S-1-5-32" # Actually the Sid of a specific service account and not of the System account  
$i = 0;
Get-WinEvent -FilterHashtable $filter | ForEach-Object {
    $xmlEvent = ([XML]$_.ToXml()).Event.EventData.Data;
    $xmlEvents += [psCustomObject][Ordered] @{
        TargetUserSid = [String]($xmlEvent | Where-Object {$_.Name -eq 'TargetUserSid'}).'#text';  
        TargetUserName = [String]($xmlEvent | Where-Object {$_.Name -eq 'TargetUserName'}).'#text';  
        TargetDomainName = [String]($xmlEvent | Where-Object {$_.Name -eq 'TargetDomainName'}).'#text';  
        IpAddress = [String]($xmlEvent | Where-Object {$_.Name -eq 'IpAddress'}).'#text';  
        LogonProcessName = [String]($xmlEvent | Where-Object {$_.Name -eq 'LogonProcessName'}).'#text';  
        AuthenticationPackageName = [String]($xmlEvent | Where-Object {$_.Name -eq 'AuthenticationPackageName'}).'#text';  
        TimeStamp = [String]($_.TimeCreated);
    };
    $i += 1;
    if (!($i % 1000)) {
        $xmlEvents | Where-Object {$_.TargetUserSid -eq $filterSid | Export-Csv -Delimiter ';' -LiteralPath ".\LogonEvent.csv" -Append;  
        Write-Host "`r$i Events processed - Last Event: $($_.TimeCreated)" -NoNewline;  
        $xmlEvents = @();
    };
};

    $i += 1;
    if (!($i % 1000)) {
        $xmlEvents | Where-Object {$_.TargetUserSid -eq $filterSid | Export-Csv -Delimiter ';' -LiteralPath ".\LogonEvent.csv" -Append;  
        Write-Host "`r$i Events processed - Last Event: $($_.TimeCreated)" -NoNewline;  
        $xmlEvents = @();
    };