Out of curiosity, did you observe an increase in performance from unzipped vs zipped vectors? I've found that most of the time things like caches are completely dominated by other factors, but I've only ever found things like that out through testing.

This new `HashMap` struct is significantly larger than the old one (7 => 17 words) which is slightly worrisome. I don't think that it's that large of a concern, but it probably shouldn't be overlooked.