I had a case where tar was too slow for my needs. Rust did let me cobble the right syscalls and threads together to make it more HDD-friendly and faster while forcing me to handle all the gritty filesystem error cases from the start. Lo and behold, about 4 times faster on an idle system and orders of magnitude faster on a busy system. It just would not have been possible to do it by combining shell utilities and too finicky in C.
That's the thing with Rust, it makes you work hard right from the start to make everything right, but when you have something working it's usually fast, too.
