We had that thought too. I'll have to try dig out what the tablets were to find out exactly what type - this would have been 3 or 4 years ago now. We sort of ruled that out because:

The other workaround to get a speed boost was the user to uninstall and reinstall the app (and then wait for all the data to download again) but that didn't fly because the users would delete before they'd synced off all their data and then data would go missing.

This was all despite having VACUUM running whenever the app started.

Whether it was bad flash or no, we still had to try resolve it as the client wouldn't buy new hardware until we could prove that we had the knowledge to make the problem go away first :/