Benchmarks are outdated#29

The current stdlib `HashMap` is a [wrapper]( https://github.com/rust-lang/rust/blob/143eaa8d441641251ab41ed73deaba0d8d0cf4a5/library/std/src/collections/hash/map.rs#L6) for `hashbrown`. It uses `AHash` which is much faster than the previous `SipHash`. > QP-tries are as fast or a bit faster as Rust's HashMap with the default hasher Therefore, This may no longer be right.