y4K518QN Edit

#Require -RunAsAdministrator
#Require -version 7
Set-StrictMode -Version 4

# Made this a bit easier to read by using specific methods (pretty sure your start time is just doing 5 days in past)
$start = (Get-Date).AddDays(-5)
$end   = (Get-Date).AddSeconds(-1)


$homedir = "$env:HOMEDRIVE\SCRIPTS\EventLog-Parallel"
# New-Item -Force doesnt overwrite directory, so you can skip the test-path
New-Item -ItemType Directory -Path $homedir -Force | Out-Null

# Instead of a bunch of if statements, and your filenames all follow same pattern, this is just a hashtable
# The only thing that changes in the if statements is the filename part, so we're mapping the log file name to the filter properties
$Map = [hashtable]::Synchronized(@{
    'SystemError'            = @{ LogName = 'System'; Level = 2; StartTime = $start; EndTime = $end }
    'SystemWarning'          = @{ LogName = 'System'; Level = 3; StartTime = $start; EndTime = $end }
    'SystemInformation'      = @{ LogName = 'System'; Level = 4; StartTime = $start; EndTime = $end }
    'ApplicationError'       = @{ LogName = 'Application'; Level = 2; StartTime = $start; EndTime = $end }
    'ApplicationWarning'     = @{ LogName = 'Application'; Level = 3; StartTime = $start; EndTime = $end }
    'ApplicationInformation' = @{ LogName = 'Application'; Level = 4; StartTime = $start; EndTime = $end }
    'Security'               = @{ LogName = 'Security'; Level = 0; StartTime = $start; EndTime = $end }
})

$error.Clear()

$Map.Keys | Foreach-Object {
    $filename = "$homedir\${name}_$($filter.StartTime.ToString("yyyy-MM-dd_HHmmss")).json"

    # Rather than doing Foreach-Parallel, we're just doing start-job for each of them so we can pass parameters to the threads
    Start-Job -Name $_ -ScriptBlock {
        param($filter,$filename)

        # Null coalescer instead of try/catch (idk this might break im just fuckin around)
        $ev = (Get-WinEvent -FilterHashtable $filter -ErrorAction SilentlyContinue |
               Select-Object TimeCreated,LogName,ProviderName,Id,RecordId,Message) ?? $null

        $ev | ConvertTo-Json | Out-File $filename -Force -Confirm:$false
    } -ArgumentList @($Map[$_], $filename) | Out-Null
}

# This will spit out empty if there are no errors, so no if statements really needed
$error | Foreach-Object {$_}