SQLite3 databases get messy over time (especially if there’s churn on the database).
I’ve noticed that “vacuuming” them from time to time can speed up searching in Squeezebox Center… so I have the following cron job (as root):
file /var/lib/squeezeboxserver/cache/*.db | grep SQLite | cut -d: -f 1 | xargs -I % sqlite3 % vacuum
Hope that helps 🙂