Bit late, but I made a small program that did network and file io as well as using a variety of containers and running system commands. I couldn't get the default release over 650kB. Using a single codegen unit lto strip and panic=abort got that down to 432kB. Using build-std didn't get it any smaller still. When I added optimization for size was the only way I got build-std to shrink things any further than the other options alone, and that only got me 10kB. My conclusion is that build-std is not a substantial contributor. Using std seems to add 300kB-500kB depending on how much you use. That seems like a lot to me because I am old, but elf binaries add several kB of header so maybe I should stop worrying so much.