I got involved in hauling for the current CG (first time for a long time), mostly in Open. NPCs seem to have had their AI nerfed!
It's been like this at busy stations for years - the problem is that the mailslot is a terrible piece of design, so if you're running (as the NPCs do) a fairly cautious traffic pattern where either one large ship is traversing the slot, or two small ships are going through one each way, you get about 1 ship/minute as your rate.
Once it gets higher than that, ships will queue and build up indefinitely even if everything is going well; if you get a player interrupting the traffic pattern and causing an NPC to crash into the side of the dock to avoid them, or if the station decides that one of the NPCs waiting to depart is loitering and blows them up and then the wreckage from that drifts into the slot, it gets progressively worse.
Obviously this is more likely in Open because the chances are the instance has existed for longer, whereas in Solo (or Open, away from a CG) at least it starts off empty, but you can get it in Solo in the right places with a little patience.
There isn't really a good solution:
- NPCs use the same flight routines as our docking computers, so making them less cautious to speed up throughput will just end up in more "my docking computer killed me again" threads.
- keeping the NPCs on the pads until they have a departure slot will eventually just clog up all the pads so no-one can dock. Then let everyone launch, and then start issuing clearance for docking again. Unfortunate if, as a player, you arrive just as the pads are getting full and you have to wait (immersively) for about 20 ships to launch.
- tightening up traffic control for players so that even if you're not using a docking computer you have to fly the pattern by the book will just be frustrating
- the stations rotate too fast for external landing pads to be viable, and redesigning them is of course completely out of the question
- reducing the number of NPCs substantially for the busy instances would make "normal" instances completely dead - imposing a general (very low) cap on NPCs per instance if there's a station about might be an option