I'm more so interested in performance and size comparisons.

Most different implementations of the coreutils have different goals in mind. GNU's implementation, as is common of GNU is to treat memory for performance, and busybox's attempts to achieve the converse. — so what is the purpose of this one? simply being written in Rust?

How does it compare to the established ones?

Rust: 73M source: https://packages.debian.org/experimental/rust-coreutils

C: 17M https://packages.debian.org/unstable/coreutils

Note that no size optimization that been done and there is a lot ways to do it in Rust https://github.com/johnthagen/min-sized-rust

In term of performance, well, it depends on the binary. For example for cp, most of the time is spending copying the files. For the factor command, some work happened to make it faster https://github.com/uutils/coreutils/commits/master/src/uu/fa... (getting closer).

Using Rust also opens some great capabilities like parallelism. But this makes sense only for complex commands. For example, doing a parallel "df" isn't super interesting (I tried it was too expensive just to start threads to do it).

Anyway, performances should be a focus but only after correctness is implemented.