How to Improve Speed When Saving FileInfo Objects to File in PowerShell

Discover how to efficiently save file lists in PowerShell without wasting time, using effective methods for working with `FileInfo` objects.
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This video is based on the question https://stackoverflow.com/q/73200573/ asked by the user 'Dougal' ( https://stackoverflow.com/u/1443448/ ) and on the answer https://stackoverflow.com/a/73256318/ provided by the user 'Dougal' ( https://stackoverflow.com/u/1443448/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Improve Speed When Saving FileInfo Objects to File in PowerShell

Are you having trouble saving file lists in PowerShell? If you're dealing with large FileInfo objects, you might have noticed that the process can be painfully slow. This guide aims to address the common problem of sluggish file saving and provide an efficient solution that will save you valuable time.

The Problem: Slow File Saving with FileInfo Objects

In a recent project to sync files between USB drives and network storage using PowerShell commands, I encountered an issue that troubled me greatly. My goal was to track files effectively and emulate robust software behaviors like FreeFileSync. However, when using the command Get-ChildItem <Path> -Recurse -File, which generates over 12,000 FileInfo objects, the task of saving this data to a CSV file took over three minutes—and it wasn't due to the file writing process itself.

Interestingly, the data retrieval completed in under five seconds, which suggested the real bottleneck lay in the conversion step, specifically with the VersionInfo property of the FileInfo objects.

The Solution: Optimize File Properties to Speed Up Saving

After some investigation and testing, I discovered an effective solution to significantly reduce the save time. Here’s how:

1. Select Only Essential Properties

By using the Select-Object cmdlet, you can filter out unnecessary properties when saving your FileInfo objects. In my case, I initially collected all properties, which included the VersionInfo that caused the slowdown.

Instead of using all properties, I modified my command to select only the essential ones:

[[See Video to Reveal this Text or Code Snippet]]

2. Performance Improvement

This simple change had dramatic results. By focusing solely on FullName, Length, and LastWriteTime, the save time was drastically reduced to under three seconds.

3. Investigate Script Properties

My further investigations suggested that the VersionInfo property of the FileInfo object was responsible for the sluggishness in conversion. When I ran the same command and included all other properties, excluding VersionInfo, save times still remained under three seconds.

Conclusion

If you find yourself struggling with slow file saving processes in PowerShell, consider following these steps:

Limit the properties you collect by carefully selecting only what you need (e.g., FullName, Length, LastWriteTime).

Avoid using properties that make your process significantly slower, specifically large script properties like VersionInfo.

This experience not only enhanced the performance of my scripts but could potentially save you a lot of time too. Happy scripting!

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