I have observed that sqlite-based applications experience a significant delay during the connection's commit() call.

At least, that is the case for my N810 with Diablo, where the rootfs is stored on a class 4 micro-SD card.

As reported here, I was able to turn the multilist application from "frustratingly slow" to "perfectly usable" by adding

to the SQL code.

I wonder if this can be used in general for Maemo applications (such as my own SplitTheTab, given that the database is stored in Flash memory.

This may appear to be faster, but it won't really be safe. The delay you're witnessing will most likely be down to fsync() (and other) calls, which are slow as they actually force writing of the data to storage.