FileVersionInfo.GetVersionInfo ().ProductVersion performance

I have an app that calls FileVersionInfo.GetVersionInfo (<filename>).ProductVersion for all the files in a folder (90 files total).  

After rebooting my PC, the first time I run this app, the 90 calls take 5 seconds.  The second time they take .2 seconds.   Can anyone explain the performance difference.  Obviously something has been cached, but what?

The reason I'm asking is that our users turn on their PC in the morning, start this app and leave it running all day.  I'm trying to improve the startup performance of the app.
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wile_e_coyoteAsked:
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iboutchkineCommented:
When you run the app the first time CLR under .NET Framework compiles the piece of code that you are running. THe second time if compilation was done before CLR does not do it. The more you will run your app under .NET Framework, the faster it will run up to the point where everything is compiled. The first time is the slowest
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grayeCommented:
yes, it could be the "just-in-time" compiler that's causing the effect.  But if so, that would only apply to very first time.  

On the other hand, it might just be the File System cache that's doing the trick...  files are cached up after the first run, making subsequent runs go much faster.

But let's talk about optimization...

You can use the FileSystemInfo object to pull all the "directory" information of the files in a folder into an array with a single call.  This *might* prime the pump to make calls to FileVersionInfo go faster (I haven't tried it)
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ptmcompCommented:
I had the same effect in native Win32 code. It must be caused by the underlying Windows API.
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