Get-ADUser takes too long when filtering and using IF ELSE statements

Question

A while ago I've posted a question about exporting specific users information from AD to .CSV file (here). Thanks to the help of Santiago Squarzon I managed to make it work and filter just the way I want, except for one small detail - it takes the script 13 hours to finish executing. I modified some filters, removed one if statement and reduced that time to around 8.5h, but it's still unacceptable for me.

Short summary: I want to export all (enabled) AD users with employee number attribute present. If it's not present, then to check other attribute and so on, total of 5 nested if statements. Then export it to a .CSV file.

Could you take a look at below part of the code and help optimizing it? I believe there is around 150k user accounts to check.

$name = Read-Host -Prompt "Please enter the name for output file."
$filename = $name + ".csv"      
$param = @{
    LDAPFilter = "(&(!extensionAttribute9=0)(!employeenumber=svc)(!(useraccountcontrol:1.2.840.113556.1.4.803:=2)))"
    ResultPageSize = 500
    Properties = @(
        'businesscategory'
        'extensionAttribute4'
        'extensionAttribute9'
        'extensionAttribute13'
        'employeenumber'
    ) 
}
'DOMAIN1','DOMAIN2','DOMAIN3','DOMAIN4' | ForEach-Object {
    $param['Server'] = $_
    foreach($user in Get-ADUser @param) {
                if($user.EmployeeNumber -ne $null){
            [pscustomobject]@{
                Name                 = $user.Name
                SamAccountName       = $user.SamAccountName
                UserPrincipalName    = $user.UserPrincipalName
                BusinessCategory     = $user.businesscategory  -join ", "
                extensionAttribute4  = $user.extensionAttribute4 -join ", "
                extensionAttribute9  = $user.extensionAttribute9 -join ", "
                extensionAttribute13 = $user.extensionAttribute13 -join ", "
                DistinguishedName    = $user.DistinguishedName
                employeenumber       = $user.employeenumber
                Enabled              = $user.Enabled
                Domain               = $_ # Adding the Domain of this user here
        }} else {
            if($user.businesscategory -ne $null) {
                [pscustomobject]@{
                    Name                 = $user.Name
                    SamAccountName       = $user.SamAccountName
                    UserPrincipalName    = $user.UserPrincipalName
                    BusinessCategory     = $user.businesscategory  -join ", "
                    extensionAttribute4  = $user.extensionAttribute4 -join ", "
                    extensionAttribute9  = $user.extensionAttribute9 -join ", "
                    extensionAttribute13 = $user.extensionAttribute13 -join ", "
                    DistinguishedName    = $user.DistinguishedName
                    employeenumber       = $user.employeenumber
                    Enabled              = $user.Enabled
                    Domain               = $_ 
                }} else {
                    if($user.extensionAttribute4 -ne $null){
                        [pscustomobject]@{
                            Name                 = $user.Name
                            SamAccountName       = $user.SamAccountName
                            UserPrincipalName    = $user.UserPrincipalName
                            BusinessCategory     = $user.businesscategory  -join ", "
                            extensionAttribute4  = $user.extensionAttribute4 -join ", "
                            extensionAttribute9  = $user.extensionAttribute9 -join ", "
                            extensionAttribute13 = $user.extensionAttribute13 -join ", "
                            DistinguishedName    = $user.DistinguishedName
                            employeenumber       = $user.employeenumber
                            Enabled              = $user.Enabled
                            Domain               = $_
                    }} else {
                        if($user.extensionAttribute9 -ne $null){
                            [pscustomobject]@{
                                Name                 = $user.Name
                                SamAccountName       = $user.SamAccountName
                                UserPrincipalName    = $user.UserPrincipalName
                                BusinessCategory     = $user.businesscategory  -join ", "
                                extensionAttribute4  = $user.extensionAttribute4 -join ", "
                                extensionAttribute9  = $user.extensionAttribute9 -join ", "
                                extensionAttribute13 = $user.extensionAttribute13 -join ", "
                                DistinguishedName    = $user.DistinguishedName
                                employeenumber       = $user.employeenumber
                                Enabled              = $user.Enabled
                                Domain               = $_
                        }} else {
                            if($user.extensionAttribute13 -ne $null){
                                [pscustomobject]@{
                                    Name                 = $user.Name
                                    SamAccountName       = $user.SamAccountName
                                    UserPrincipalName    = $user.UserPrincipalName
                                    BusinessCategory     = $user.businesscategory  -join ", "
                                    extensionAttribute4  = $user.extensionAttribute4 -join ", "
                                    extensionAttribute9  = $user.extensionAttribute9 -join ", "
                                    extensionAttribute13 = $user.extensionAttribute13 -join ", "
                                    DistinguishedName    = $user.DistinguishedName
                                    employeenumber       = $user.employeenumber
                                    Enabled              = $user.Enabled
                                    Domain               = $_
                            }} else {
                                if($user.SamAccountName -like "*_A*"){
                                    [pscustomobject]@{
                                        Name                 = $user.Name
                                        SamAccountName       = $user.SamAccountName
                                        UserPrincipalName    = $user.UserPrincipalName
                                        BusinessCategory     = $user.businesscategory  -join ", "
                                        extensionAttribute4  = $user.extensionAttribute4 -join ", "
                                        extensionAttribute9  = $user.extensionAttribute9 -join ", "
                                        extensionAttribute13 = $user.extensionAttribute13 -join ", "
                                        DistinguishedName    = $user.DistinguishedName
                                        employeenumber       = $user.employeenumber
                                        Enabled              = $user.Enabled
                                        Domain               = $_
                                }}
                                }
                            }
                        }
                    }
                }
                }
} | Export-Csv "$env:userprofile\Documents\$filename" -Delimiter ';' -NoTypeInformation

'DOMAIN1','DOMAIN2','DOMAIN3','DOMAIN4' are (I believe) 4 different sub-domains in one domain tree: domain1.test.com, domain2.test.com etc.

Answer 1

Not meant as an answer but to prove a point, will delete after.

$user = [pscustomobject]@{
    SamAccountName = '_A'
    EmployeeNumber = $null
    businesscategory = $null
    extensionAttribute4 = $null
    extensionAttribute9 = $null
    extensionAttribute13 = $null
}

# your code
if($user.EmployeeNumber -ne $null){ $user }
else { if($user.businesscategory -ne $null) { $user }
else { if($user.extensionAttribute4 -ne $null){ $user }
else { if($user.extensionAttribute9 -ne $null){ $user }
else { if($user.extensionAttribute13 -ne $null){ $user }
else { if($user.SamAccountName -like "*_A*"){ $user }}}}}}

# can be reduced to one condition
# (Not implying this is faster)
if(
    $user.EmployeeNumber -or
    $user.businesscategory -or
    $user.extensionAttribute4 -or
    $user.extensionAttribute9 -or
    $user.extensionAttribute13 -or
    $user.SamAccountName -like "*_A*"
) {
    $user
}

# but above can be translated to the following LDAP Filter, which is faster
(|
    (EmployeeNumber=*)
    (businesscategory=*)
    (extensionAttribute4=*)
    (extensionAttribute9=*)
    (extensionAttribute13=*)
    (SamAccountName=*_A*)
)