Right, sorry, I didn't mean to imply that you should have covered stack allocation in your post. I think your post covers the right material to make its point.

This is more of a side comment about a different question, perhaps "ok fine, but then what are the language differences that could be performance-relevant for one language or the other, even if (as you say) they don't lead to a yes/no answer for your original question?"

The ones I think, personally:

1. crates.io makes it easy to use complex data structures. Basically this argument https://bcantrill.dtrace.org/2018/09/28/the-relative-perform...

2. Rust's safety guarantees making it easier to maintain more dangerous things over time.

3. On the C side, there's a lot more cultural understanding overall of how to use the language to get good performance results

4. It might be easier to find people who are experienced in heavily optimizing C code as opposed to Rust code.