Powershell and writing files (how fast can you write to a file? )

Hi there,

I’ve been working for some time on a tool similar to PAL from mike lagase in order to automate the analysis of loadgen runs.

While doing this I had to write large files with PowerShell and was not impressed with the result.

I thought I’d share the problem and solution with the community.

There are at least four ways of writing files with PSH:

· use the ‘>>’' alias that calls into the out-file cmd-let

· use export-csv

· use .Net

So let’s say I want to write 10000 lines into a file.

Method 1: use the >> operator

$s=”some text”

1..10000 | % {
$s >> ".\test.txt"

This way you actually open and close the file 1000 times.

Method 2: use out-file to write an Array

1..10000 | % {
$a+=[Array] $s

$a | out-file ".\test.txt"

This way actually writes once, using powershell.

Method 3: use export-csv to write an Array


1..10000 | % {

      $a+=[Array] $s


$a | export-csv "t.txt"

Export-csv can also write the array for you

Method 4: use .Net StreamWriter to write the file

$stream = [System.IO.StreamWriter] "t.txt"

1..10000 | % {




The StreamWriter object from .Net also does the work nicely.

Conclusion: how fast ?

I tried all methods on my laptop, and here is what I got:


Time to completion


29 s

Outfile and [Array]

27 s


22 s


1.5 s

Well results speak by themselves, if you are in a hurry, use .Net StreamWriter !


Next, check that with Powerhell v2!