What else is happening on your BBB system when you are running these tests? Are there background processes with higher priority which could cause suspension of your DB process? Are you writing your DB to disk? Could caching in memory followed by committing to disk cause a delay? SQLite has some tuning parameters that can affect these things; the default implementation of the QSQLITE driver may not be setting them appropriately for your application. You can modify these values through SQL PRAGMA statements.