This post is intended as a tour of various techniques (not necessarily all practical) of reducing program size, but if you demand some conclusion, the pragmatic takeaway is that:

Compile with --release.
Before distribution, enable LTO and strip the binary.
If your program is not memory-intensive, use the system allocator (assuming nightly).
You may be able to use the optimization level s/z in the future as well.
I didn’t mention this because it doesn’t improve such a small program, but you can also try UPX and other executable compressors if you are working with a much larger application.

Via http://nicolas-delsaux.hd.free.fr/Shaarli/?x0e0Fw