The leveldb page shows mixed results wrt sqlite3 - I would say that it is generally faster that sqlite3 based on the results. There is no comparison to sqlite4.

Most notably in large value operations, and also slightly in random reads, sqlite3 wins. In in other benchmarks however, leveldb is faster.

The leveldb page notes that they perform poorly with large values due to the increased I/O that is done. The relatively poor random read performance isn't discussed but my guess is that it's due to having to fetch a compressed page of data that contains values for other keys, thus leveldb is doing "more work" than strictly necessary.