Late game problems or no, the 1/18 version is an enormous improvement.
To answer your question:
Also, odd lag issues with >100 ping. Probably just the price of doing business with the Civ 5 netcode.
How is it an improvement? I'm curious, esp. since I don't have a reliable means of debugging MP.
Yeah, high ping will create problems, big-time. Since I've rewritten the kstream I hope the imperium issue is fixed. I also think the smaller save/kstream size will help with lag resistance (we were sending a LOT of duplicated data across the network).