You were the one that cynically asked if the advertised performance improvements were real or imaginary, not me.

To your point, many of the improvements from Rust-based tools appears to come from the ability to express performant semantics safely and elegantly in the language. You could write an equivalent in C, but the Rust one comes naturally, can be expressed at a higher level with better abstractions, and often comes out with top-tier performance before even investing in microoptimizarions (as long as the Big-O performance is in check).