I would recommend looking into dtrace or other observability tools to figure out what to optimize next. So far you have basically had to guess where the slownes

I would recommend looking into dtrace or other observability tools to figure out what to optimize next. So far you have basically had to guess where the slowness is and optimize that. Lastly, how long does it take to make a copy of an already prepared 1b row SQLite file?that seems easier than generating a new one.