Bad Cargo Wagon Performance in Vanilla

[dabalciunas]

When building the prototype of a megabase with huge trains, I've noticed that I could use a single Cargo Wagon on 2 pieces of rail as a big 2 x 6 chest. I needed this because the 1x1 chest does not satisfy several design conditions as a temporary buffer for unloading from train directly to factories, without using belts.

Furthermore, with the wagon I was able to place inserters around and "under" the cargo wagon, perfect for balanced and fast loading/unloading, which makes this "trick" very interesting.

However, I've also noticed that this Cargo Wagon has a much worse CPU usage performance than common 1x1 chests for inserting / removing items.

There are multiple mods offering better chests, but I just wanted to play PURE vanilla as my challenge. Pure vanilla megabase.

So this brings me to the following conclusions:

- Vanilla could get an additional 1x2 chest. Not 2x2 nor 3x3, just 1x2, 1x3, 1x4 would do, especially for factory designs using trains. I mean, we can send rockets to space in Factorio, but we can't have any flexible chest options? What about dynamically grouping/combining neighboring chests up to a certain amount, say 4 chests in any arrangement to form a single combined chest entity? And please keep CPU usage as low as a normal chest would?

- The use of a cargo wagon as a chest was a workaround for having no flexible chest sizes in vanilla. But it also shows how cargo wagons need an urgent performance check. They are indeed one of the reasons why the best performance megabase isn't made of any trains: it is made only of belts... that's a bummer, trains are supposed to be more CPU efficient than huge chunks of belts, otherwise what is their purpose? It's similar to the performance paradox of solar panel farms vs. nuclear power plants. I'm not even mentioning about cargo wagon capacity, just the insertion/removal CPU usage/performance compared to normal chests.

[robot256]

FYI the performance penalty for cargo wagons comes from the fact that they can have slot filters applied. Even if you didn't use any filtered slots, the game has to double check every time something is inserted. So the main advantage of a new type of chest would be that it would have slot filters disabled.

[boskid]

All rolling stock when built are part of some train, even if there are no locomotives in it. Having unconnected cargo wagon still causes some extra trains to exist and trains are updating every tick even when in manual mode because movement of trains is part of its update: if you have moving train and locomotive gets destroyed you are left with another train that is still moving. I am not convinced this use case is interesting enough to be handled with extra care given that deactivating train would create a lot of corner cases when train has to be activated again.

[astroshak]

While I don’t think that modifying the game to use a cargo wagon like that is the best thing to do, I would love to see rotatable 1x2, 1x3, 1x5, and 1x6 chests in game, even if they are only made of wood and thus have 8 slots per tile.