(author)
In the post I say I did write sqlelf which is just that, sqlite + virtual tables prior to this.
For my own edification I often let performance & size slip to see if I can re-imagine something simpler from the start from a complete new direction;
This is often the greenfield hubris because it doesn't have all the same battle-scars of the full implementation so I try to make sure I take a very different approach to make it worthwhile :)
Then I just have faith that performance and size can always be improved over time.