Looking to speed up this PowerShell Function - loops

Question

I'm running the following code to pull data from SCOM 2012 and using an exported spreadsheet from SCCM 2012, output servers which are pending reboot along with their SCCM maintenance window for automated scheduled reboots.
The code takes around 5-8 minutes to run and I was wondering if there was any way to speed up the process. The code running under Begin Loop is the bottle neck.
Function Generate-RebootData{
IF(Get-Command Get-SCOMAlert -ErrorAction SilentlyContinue){}ELSE{Import-Module OperationsManager}
"Get Pend reboot servers from prod"
New-SCOMManagementGroupConnection -ComputerName ProdSrv
$AlertData = get-SCOMAlert -Criteria `
"Severity = 1 AND ResolutionState < 254 AND Name = 'Pending Reboot'" |
Select NetbiosComputerName
"Get Pend reboot servers from cert"
#For cert information
New-SCOMManagementGroupConnection -ComputerName CertSrv
$AlertData += Get-SCOMAlert -Criteria `
"Severity = 1 AND ResolutionState < 254 AND Name = 'Pending Reboot'" |
Select NetbiosComputerName
"Remove duplicates"
$AlertDataNoDupe = $AlertData | Sort NetbiosComputerName -Unique
"Create hash table"
$table = #{}
"Populate hash table"
Import-Csv D:\Scripts\servers2.csv | ForEach-Object {
$table[$_.Computername] = $_.'Collection Name'}
"Create final object"
$result = #{}
"Begin Loop"
$result = $AlertDataNoDupe | ForEach-Object { [PSCustomObject] #{
Server=$_.NetbiosComputerName
MaintenanceWindow=IF($table[$_.NetbiosComputerName]){$table[$_.NetbiosComputerName]}
ELSE{"Not found!"}
PingCheck=IF(Test-Connection -Count 1 $_.NetbiosComputerName -Quiet -EA SilentlyContinue)
{"Alive"}
ELSE{"Dead"}
LastReboot=Try{
$operatingSystem = Get-WmiObject Win32_OperatingSystem -ComputerName `
$_.NetbiosComputerName -ErrorAction Stop
[Management.ManagementDateTimeConverter]::ToDateTime(`
$operatingSystem.LastBootUpTime)}
Catch{"Access Denied!"}
} }
}

Answer 1

You should perform the PingCheck first, and only if that succeeds move on with the Get-WmiObject call - there's no need to contact a machine if you've just determined that it's "dead".
...
$result = $AlertDataNoDupe | ForEach-Object {
# Create hashtable
$Properties = #{
Server = $_.NetbiosComputerName
MaintenanceWindow = if($table[$_.NetbiosComputerName]){
= $_.NetbiosComputerName
} else {
'Not found!'
}
}
# Perform ping check, keep as boolean
$Properties['PingCheck'] = Test-Connection -Count 1 $_.NetbiosComputerName -Quiet -EA SilentlyContinue
$Properties['LastReboot'] = if($Properties['PingCheck'])
{
try
{
# Server seems to be online
$operatingSystem = Get-WmiObject -Class Win32_OperatingSystem -ComputerName $_.NetbiosComputerName -ErrorAction Stop
[Management.ManagementDateTimeConverter]::ToDateTime($operatingSystem.LastBootUpTime)
}
catch
{
'Access Denied!'
}
}
else
{
# If server doesn't respond, declare it offline
'Computer offline!'
}
# create the object
New-Object -TypeName psobject -Property $Properties
}