Measure your app's memory footprint and look for leaks in Instruments. Then try it after invoking sqlite3_exec with:
and/or
YMMV. There are reports of performance boosts, large reductions in RAM usage, and fewer leaks. However, be careful about making adjustments without understanding the impact (for example, synchronous turns off flushing which speeds things up by a lot, but can cause DB corruption if the phone is power-cycled at the wrong time).
More here: http://www.sqlite.org/pragma.html
