Interesting. I assume the 12K excludes dependent DLLs. Do you know if on Windows there’s a DLL for the Chicken runtime library and for the C library (and others), and their size?
The Chicken DLL is about 3.4MB, of which a good deal will be relocation tables and such. I'm a Cygwin user, so my C library is included in cygwin1.dll, which is about the same size (it uses newlib, not glibc, but has to provide full Posix plus much other Linux stuff). The native Windows C library, also a DLL, is about 1MB, depending on the OS version; Chicken provides the same interface on Posix and on Windows, but much of it (fork, obviously) will throw runtime exceptions on Windows. Of course, Windows itself is also in DLLs. Chicken does not have a run-on-bare-metal option; it depends on the presence of either Posix or Windows.