I expect extensions in Rust will be much faster than those written in pgSQL, which would need to be interpreted, of course this should be validated. In addition to that, this is stdlib code in Rust, and stable, so you should be able utilize anything from the Rust ecosystem in an extension built in Rust.
There's always a trade-off of adding new languages to a project, and for simple things, Rust might not be the best choice.
The benchmarks seem to show it neck and neck with lucene, so I'd imagine faster (and with a better ranking alogrythm) than the beuild in postgres search.
There's always a trade-off of adding new languages to a project, and for simple things, Rust might not be the best choice.