I’ve recently switched Hypatia databases from internally using HashMaps to BloomFilters, resulting in a massive improvement to both efficiency and efficacy.
Before: ~520k signatures, 140+MB RAM usage
After: ~4.9m, <120MB
And there is a new stats page for the database: https://divested.dev/MalwareScannerSignatures/
It is currently only on my F-Droid repo, will be on F-Droid.org in a few days.
Feedback welcome.