Sizing issues in PSCS2/Mac

I've got a problem that's more of an annoyance than a serious problem, but if there is a solution to it that would be great.

When I save an icon in PSCS2 it saves fine but when I check the properties of it, it's about 192KBish, bigger than 40KB anyway. However this is clearly wrong as I'm able to upload them as userpics. I don't think it can be a Mac error as anything else I save, or make in different programs etc all show the correct file size. Is there something I'm doing wrong when saving or is this just something I'm going to have to suck up and deal with?

I have found this, but it deals with a windows PC.