Inserting data with `Durability::None` makes database file grow rapidly

[tqwewe]

When inserting data with the Durability::None in a commit, the database file grows extremely large compared to using something like Immediate.

Ideally, I'd like to flush the database every 10 seconds or so, as the data being stored can be recomputed and isn't super important.

Inserting a (&str, Vec<u64>) with 100,000 u64's (being inserted one at a time) results in the file growing to dozens of GB before I need to forcefully stop my app. However doing so with the Durability set to Immediate is just a few MB.