The Rust HashMap and HashSet implementations are generic over hasher: you can pick a faster one if you don't have to worry about getting ddos'd. Last I checked, the go-to fast hasher was fnv: https://doc.servo.org/fnv/
How often do I need to explain that this siphash claim of DDOS protection is utter nonsense. siphash can easily be brute forced like every insecure hash function (<256 bits), and proper DDOS protection can only be provided by a proper collision strategy. Even DJB himself does so.
Is there any way to use it directly in the source w/o having to create a Crate.toml and src dirs? Is there a getting started document? Dub recently included such a feature.
https://doc.rust-lang.org/cargo/ has installation, getting started, a reference, all of that. It needs some work, but for the basics of doing this, it's got it all.