1) After mapchange it happens that players are shown as connecting for several minutes until it finally says they timed out and removes them.
Well almost all of them are gone players. I saw it myself: I shut down OA after the game was over and then queried the server and saw my name on the server with ping 999.
So I think it should time out earlier as it wait very long to drop such.
I think this bug happens when players need to download a new map they don't have, and after they downloaded, they are said that they have been timed out. This is an old bug of the engine.
Also, about kicking ghost players faster, I think that you can tweak the sv_zombietime cvar.
2) Kicking idle players:
An issue are players that stop playing but don't leave the server. So they occupy a slot but do nothing.
It would be nice if they get kicked after something like 90 seconds without action.
Are you sure it's not already implemented with g_inactivity cvar?
