Interesting, you appear to be hitting some kind of pathological case with the `vec!` macro. Apparently it doesn't like being used with a 15,000-line literal. :P Fortunately you're right, there's a different way to do this, which AFAICT doesn't suffer from the same pathology. I replaced this:

    pub struct Choice {
        pub word: String,
        pub avg_remaining: f64,
    }

    pub fn root_choices() -> Vec<Choice> {
        vec![
            Choice { word: "roate".to_string(), avg_remaining: 60.42462203023758 },

with this:

    use std::borrow::Cow;

    #[derive(Clone)]
    pub struct Choice<'a> {
        pub word: Cow<'a, str>,
        pub avg_remaining: f64,
    }

    pub const ROOT_CHOICES: &[Choice] = &[
        Choice { word: Cow::Borrowed("roate"), avg_remaining: 60.42462203023758 },

and it brought the time of `cargo clean && cargo build --release` down from 345 seconds to 13 seconds. I consider this a compiler bug, I'll file it if I can't find an existing issue.

Oh, thanks! That is exactly what I wanted; a global constant makes more sense for this use-case.