It looks like the lag was caused by my careless use of a feature in the Lidgren network library which allows sending messages through UDP reliably (= so that they’re resent if the recipient doesn’t acknowledge receiving them). In some cases that lead to severe congestion problems, causing enormous lag not just in the chat but all the reliable messages that the game sends. Rewiring devices, picking up or dropping items and attaching/detaching items were all synced using reliable messages, and there were definitely problems with all of those even though the chat lag was the most obvious effect.
I think I’ve managed to fix the problem though: the reliable messages are now sent using a homebrew packet loss detection system which allows me to slow down or cancel the resending process entirely if it seems like the line is choking (once again thanks to Glenn Fiedler his excellent articles which have helped me quite a few times during the development of Barotrauma).
However, I haven’t yet been able to test and verify that the fix is 100% working, because I still haven’t managed to reproduce the issue when playing the game on my computer. I did host a few “real” online rounds with 4-5 players and everything was working great, but it’s still possible that the problem re-emerges when there are more players. So, I decided to upload the current build
so that I can use you guys as free testers in case you want to try a version that probably works much better than v0.2.2 while I try to get rid of any bugs in the new netcode and verify that it’s actually working.
tl;dr: Chat lag and a bunch of other networking issues probably fixed, try at your own risk by downloading the latest build here:
There’s also a bunch of other small additions and fixes in the build (such as being able to ban players and hit people in the face with a wrench).