Turnwise chat history
Recently I joined a few larger diplo games which of course include a lot of public chat. In two of these games we have reached the point that my PC is unable to load the chat history because it is just too big. Since most of the time you know which time of the game you want to refer to it would be usefull to be able to recall just a portion of the chat.
My suggestion would be to add a feature that allows you to load the chat history for just one specific turn or maybe a bunch of turns where you could choose starting and end turn.
That way the loading times would be reduced greatly and it would be way easier to find the messages you were looking for.
I hope such a thing would not be too hard to implement.