Also iirc there are improvements to those benchmarks in the pipeline, idk what happened to them (Veedrac and llogiq had something in mind).

Sure, you could hand-translate C in many cases (not regex), but that would be far from idiomatic. Most of the rust solutions try to still look Rust-y.

Regarding sse, if you care about performance and sse use a nightly compiler. That option exists. Rust nightly is still Rust.