Parallelization

[tgross35]

We probably want to benchmark where the best place to bring rayon in would be

I am thinking that we probably want to make checking for a word a single thread, but maybe checking multiple words could be parallel?

If we can do lazy creation & storage in parallel (#54), we need to put our wordlists in a RwLock... but that could be deadlock heavy.

We need some good benchmarking before this.

[tgross35]

We could also do some form of sharding - store a [Mutex<HashMap<...>>; 8] and use the first char % 8 to determine which index to use.

Or https://github.com/xacrimon/dashmap