[bestouff]

Yes there's a fixed cost because of the std library, panics unwinding code (i.e. clean recovery instead of aborting when something goes wrong), and the tendency to statically compile everything in adds some more, but in embedded context (a.k.a. "no_std") you can observe C and Rust code are very comparable.

Especially in your case you'll find Rust to be a joy to use: you'll have way more confidence in your code being able to run for months without segfaults or memory leaks. And if you have a good understanding of the C memory model using Rust will be a breeze.