Yes, we already discussed that at some point but we haven't decided yet how to implement it. We don't like how most players perform which use SQLite as their database backend, but we do like how foobar2000 performs with its custom database and ~100,000 tracks with arbitrary tag fields. Maybe others who use SQLite do something wrong, maybe SQLite isn't the right tool for the job and maybe there's a third option worth considering. Once we get some time and motivation to build some prototypes we'll hopefully find that out.