The thing where your app displays 20 stories in the homepage, but for each story it runs an extra query to fetch the author, and another to fetch the tags.

It's usually a big problem for database performance because each query carries additional overhead for the network round trip to the database server.

SQLite queries are effectively a C function call accessing data on local disk so this is much less of an issue - there's an article about that in the SQLite docs here: https://www.sqlite.org/np1queryprob.html