What folders should NOT be compressed?

Ok, I'm looking to compress some folders to save some disk space and I know from experience that some files shouldn't be compressed (as it can screw up the booting, etc.) so does anyone have a comprehensive list of what not to compress in windows 7?

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Essential Member
Hello, and welcome to the Windows 7 Forums :)
I wouldn't recommend compressing ANY hidden folder, nor the Windows folder.
You can compress the Program Files Directory as well as your personal directory (C:\Users\yournamehere)

There's better way to save disk space then using compression though.

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Microsoft MVP
Staff member
Premium Supporter
Microsoft MVP
Avoid completely if possible

Depending on how frequently a file needs to be compressed compression can have a major effect on system performance. The cost of disk storage has dropped dramatically in recent years and this, combined with the increase in capacity means there is rarely any good reason for needing compression at all and I would avoid it completely if possible.

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