Wondering about VM sizes

Hi Guys -

Looking at download sizes for Croquet today I was somewhat astonished by
the size differences in the various VMs. Looking at the VMs in Croquet I
find that the sizes for the platforms are:

        Win32: 1,090,259 bytes
        Unix:  4,174,760 bytes
        Mac:   7,332,608 bytes

I haven't looked at the details but I'm surprised to see such
differences. Do you have any ideas why the Unix and Mac VM are *that*
much larger than the Win32 VM? I can understand some of it given that
the Mac VM is a "universal" binary (probably including PPC as well as
Intel binaries) but that still leaves a factor of 3-4 which simply
amazes me.

Any explanations? Are there plugins built with either the Unix or Mac VM
which take that space and that I'm simply not building for Windows? Any
other causes?

Curious,
   - Andreas