The 3x3 can easily be done in under 5 minutes. On the highs score panel you can check the builds that people have used to beat the map, it's only a snapshot of the final state of the map, but it might prove useful to you.

I managed to do it in like 17 minutes on the 3x3 map

As far as I can tell, the game can be largely broken down into a few phases:

Phase 1: Basic start, where you're just laying down the conveyor pathway and building factories as you can afford them.
Phase 2: You have enough money to buy Centrals and Accelerators, allowing you to achieve slow persistent growth.
Phase 3: You have a million dollars, and can place down an Investor, allowing far faster growth than the Accelerator.
Phase 4: You have saved up 300 billion, allowing you to buy the 3rd Investor upgrade, and you'll quickly be able to end the level by buying The Box.

I have no idea how to speedrun this in under 20 minutes, let alone how to speedrun it in under 5 minutes.

nice table, nice to have on hand ^^

Awesome, thank you!