This is my big question, to anyone who might know: What is the most computationally expensive thing about my factory, and how can I minimize it? Is it the 200 logistics robots servicing 200 requester/provider chests per factory expansion? Is it the 70 isolated red wire networks per expansion? Is it the logistics networks at the mining outposts? Or is it simply the biter/spitter density?

Short answer: It is the sum of all.

Long answer: I really enjoyed your article, would like to see more, get access to a save etc

And I think this is a point, where we really can begin to compare the reality with the game: why don't we have just a big gigantic factory here on earth surface? I mean: we have the power, the technology to spread all over the earth, build some small villages every 3-5 kilometers, some factory complex, some agriculture, houses, streets, a shop, etc.

Why isn't it so? Why is it the opposite? Why do we have mega cities and the villages in the country are dying? (Here in Germany, especially eastern Germany we have such things, and it's happening all over the world).

The answer is, that it is just an economic aspect. It's much cheaper to build some mega cities instead of building many small.the core of the problem is, that you cannot plan everything. You build things and suddenly you see, this isn't working as planned. This is quite normal and normal planning solves this with two options: planning in some extra resources and having a time buffer.

Extra resources is in our times nearly almost money. Because if you have forgotten something, you just buy it. But this is much easier, when the distances are narrow. In Factorio you see that, when the bots need N quadratic time to do a job (N is the average distance to the "center" here). The costs explode with the distance.

The costs explode also when you do it differently: bring all stuff on a ship to an island and build a house. Now you forgot the screws, which are needed to fix the roof and you need to travel back for them. Of course here it's differently: we put in the ship much more stuff, than we really need, just in case of missing something. This is much cheaper than traveling back, but the costs are much higher, cause eventually you never need the extra stuff.

In other words: the costs in Factorio to spread exponentially (von Neumann is not the right word for it, but I don't have a better) are,
- how much time is needed to travel to that point to initiate the construction of a structure
- how much resources you need to build a structure
- how much stuff is needed to craft the items
- how much time is needed to build the items
- how much time it takes to bring the items from A to B
- how much items you need to build, that are not used, that are wasted
- how long it takes to change a plan
- how fast the changes can be produced and brought to the target
- how high are the costs for this "express delivery"

What does that mean for Factorio?
- It makes no sense to create one copy of your factory and repeat it every x tiles. We need to concentrate. A Factory every 200 tiles is much, much too thight. My experiences showed me, that it is much more like one big factory every 2000 or 3000 tiles. And that is still quite too thight.
- so it makes sense to specialize. An area for solar panels only for example. One quite, quite big area for smelting. The problem is then still, that you need too much unneeded stuff, cause you cannot really plan that.
Edit:
- not every area is equally useful. There are many reasons, why cities are build at certain places. Mainly, because their surrounding is optimal in many points; there is never only one reason!

What do we need for that?
- we need some tool to request things far away and it will be brought very, very fast. See Pneumatic delivery https://forums.factorio.com/forum/vie ... f=6&t=7150 that does exactly this.
- we need some possibility to build small outposts quite cheap and with high throughput. See ropeway thread: https://forums.factorio.com/forum/vie ... f=6&t=7977
- we need ways to go really fast from A to B. Teleporters for example.
- ways to transport a lot more stuff then yet. Packaging for example. https://forums.factorio.com/forum/vie ... f=6&t=8398
- easier ways to reduce distances in logistic network. Colored logistic: https://forums.factorio.com/forum/vie ... tic#p38564

And many more stuff.