Being early access means that stuff like this will happen. The blog post however makes me nervous. Unless I'm mistaken and those optimizations haven't been added to the EA build but only experimental, then they haven't really solved anything!
When I host a game and my friends connect they both have a nice ping of ~10ms. My network connection is 500/500 mbit/s with ~3 ms when speed testing on serveres around the country!
Within a few hours of gameplay they start to lag around, especially when driving. The base doesn't have to be large at all! If they quit and rejoin it may run better again for a few hours.
My game (as host) runs smoothly, the CPU isn't even maxed out. If the game only supports a few threads, then a dedicated server might fix the issues, but it still seems like networking (UE replication) have been, and still is, badly implemented!
The game is not that different from Ark (another UE game) when it comes to replicating inventories and any form of character movement.
Sure Ark have no conveyor belts, but it still ran much more smoothly when first released. And they have inventories as well!
When you're in a vehicle and doesn't look at a conveyor belt at all, then there's no reason to replicate anything but character movement, yet my friends still complains that they lag around, even when far away from the main base.
When you look at a conveyor belt it only needs to replicate when a new item should be shown on the belt and when the last item should be shown, position doesn't even have to be accurate, only item type and count.
The worst problem though is structures that gets spawned but not drawn for some of the clients before they quit and rejoin. Physics work, but the model ain't drawn.