`New-Object` cmdlet vs `[PSCustomObject]`

[iRon7]

Type of issue

Missing information

Feedback

Even it is implied in the section Avoid wrapping cmdlet pipelines section and covered in the Everything you wanted to know about PSCustomObject / Legacy approach. Creating PSCustomObject is a very common use case and the impact of using the New-Object cmdlet vs [PSCustomObject]@{ ... } type initiator is quite severe:

Measure-Command {
    for ($i = 0; $i -lt 1e6; $i++) {
        $resultObject = [PSCustomObject]@{
            Name = 'Name'
            Path = 'FullName'
        }
    }
}

Measure-Command {
    for ($i = 0; $i -lt 1e6; $i++) {
        $resultObject = New-Object -TypeName PSObject -Property @{
            Name = 'Name'
            Path = 'FullName'
        }
    }
}

Syntax	Windows PowerShell (5.1)	PowerShell 7.4.5 (Core)
New-Object	90 secondes	39 secondes
[PSCustomObject]	8 secondes	5 secondes

I recommend to make a special note in this performance document too.

Page URL

https://learn.microsoft.com/en-us/powershell/scripting/dev-cross-plat/performance/script-authoring-considerations?view=powershell-7.4

Content source URL

https://github.com/MicrosoftDocs/PowerShell-Docs/blob/main/reference/docs-conceptual/dev-cross-plat/performance/script-authoring-considerations.md

Author

@sdwheeler

Document Id

9818d91b-8c5f-337a-f5e1-7a40abd5fd1a

[iRon7]

Actually this presumably counts for any object creation including something like: New-Object System.Drawing.Size(800, 600) --> [System.Drawing.Size]::new(800, 600)

Fyi, the related StackOverflow question I was trying to answer: https://stackoverflow.com/q/79119400/1701026

[sdwheeler]

@iRon7 I was thinking the same thing about new()' vs 'New-Object.

Another example:

Measure-Command {
    $test = 'new() method'
    for ($i = 0; $i -lt 1e6; $i++) {
        $sb = [System.Text.StringBuilder]::new(1000)
    }
} | Select-Object @{n='Test';e={$test}},TotalSeconds

Measure-Command {
    $test = 'New-Object'
    for ($i = 0; $i -lt 1e6; $i++) {
        $sb = New-Object -TypeName System.Text.StringBuilder -ArgumentList 1000
    }
} | Select-Object @{n='Test';e={$test}},TotalSeconds

Test         TotalSeconds
----         ------------
new() method         4.67
New-Object          21.56