At risk of clouding the issue with facts, here are the sizes for my project, tomboy-ng, all built with all debug off.
4349840 Feb 20 21:01 tomboy-ng64 --- Linux64
3310060 Feb 20 21:01 tomboy-ng32 --- Linux32
3013632 Feb 20 20:57 tomboy-ng32.exe
4182528 Feb 20 20:56 tomboy-ng64.exe
6411704, stripped to 3460140 Mac 32bit, carbon
I applied strip to them all, no difference on windows and Linux. (Wow, strip did not complain about being pointed to a windows binary!)
So, yes, mine show same pattern but not by same margin.
David