This entire article is nonsense. To a first approximation, the speed of your program in 2021 is determined by locality of memory access and overhead with regard to allocation and deallocation. C allows you to do bulk memory operations, Rust does not (unless you turn off the things about Rust that everyone says are good). Thus C is tremendously faster.
There is this habit in both academia and industry where people say "as fast as C" and justify this by comparing to a tremendously slow C program, but don't even know they are doing it. It's the blind leading the blind.
The question you should be asking yourself is, "If all these claims I keep seeing about X being as fast as Y are true, then why does software keep getting slower over time?"
(If you don't get what I am saying here, it might help to know that performance programmers consider malloc to be tremendously slow and don't use it except at startup or in cases when it is amortized by a factor of 1000 or more).
There is this habit in both academia and industry where people say "as fast as C" and justify this by comparing to a tremendously slow C program, but don't even know they are doing it. It's the blind leading the blind.
The question you should be asking yourself is, "If all these claims I keep seeing about X being as fast as Y are true, then why does software keep getting slower over time?"
(If you don't get what I am saying here, it might help to know that performance programmers consider malloc to be tremendously slow and don't use it except at startup or in cases when it is amortized by a factor of 1000 or more).