I know what you said. I just don't think it was interesting. If by idiomatic rust, you mean generic "unoptimized" Rust being slower than optimized C, then yeah. No shit.

On a similar note, I don't think it's worth talking about C as if the only C being written is highly optimized hand rolled assembly style of C. That's one in a thousand projects.

Now, as for the benchmarks game, you mean 3 of 6 comparisons in favor of Rust. Rust is winning the benchmarks against C there.

I had a look and the top Rust and C entries are using the same pcre2 library in regex-redux. Same for pidigits where both libraries are using GMP.

The only library difference I can see is that the C entries are using OpenMP and both Rust entries are using Rayon. Now, you could claim that using Rayon gives Rust an unfair advantage. But an entirely userland library beating an industry standard with support from compilers is not a good look for C.