The assumption is that "Compress PDF" found in the Preview PDF menu is the same as the Compress you refer to. My friend claims to (I haven't actually seen him do it) use the Compress PDF in Preview and got a 17 MB file down to 600 KB.
When I try to compress the file it makes no significant change in file size. Is my friend's system set to a different compression ratio or could there be a difference between these two types of 'compress' or something else?
I've looked online to see if there is a way to adjust the compression ratio. Certainly nothing obvious or user friendly. Not that I'm not capable of command line, but I don't want to go that route. My friend knows much less about computers than I do, so I'm sure he hasn't made any adjustments to his settings.
If you just need a 72dpi resolution and a really quick way to compress your file. I would recommend you http://smallpdf.com! It certainly doesn't offer too many features but is enough for 90% of my files.