The clustered primary key (NO ROWID) setup that came in with SQLite version 3.8.2 (2013-12-06) makes it very fast indeed when used for a large persistent key-value store.

And later improvements have just continue to accrue.

This from a guy who just implemented a persistent object cache with it, and was blown away by how well it works. And my requirement was all SQLite versions 3.7 and later, so there's conditional code. (ROWID or not, UPSERT or not).

Not to mention there are probably ten or more of these databases in your mobile phone. We haven't heard, at least I haven't, about any monstrous day-1 vulnerabilities in this code.

A really good design choice, SQLite is, if your application can live with its local file system requirement.