The problem is not how much things the engine renders, because games with far larger environments and even more complex effects run fine on my rig. Not stellar but fine. DoS 2 ran excellently and this game isnt that much more complicated then that.
The problem - in my very limited understanding - is that the ram doesnt remove things that got into it and are not needed anymore. They just keep pilling on and stay in the ram. So even if you had a fog of war after a bit more time all the things that got rendered would pile up and cause the same effect. There are probably some other issues too but apart from noticing these slowdowns i cant offer anything else. The programmers in the team will know much better. This is an early version of the game, things are not running as well as they should - yet. Its a work in progress, more optimization will make it much better. And it would be very surprising if we had to wait a whole year or full release.
This is a standard issue in early builds.
