Set graphic details to maximum. Skipped the intro mission, started directly in the main "hub". Game SEEMS to be unplayable at first sight due to VERY low FPS. Switched graphics one level "down". I dont know what really happens, but it seems as if graphic data is slowly loaded(cached?) somewhere. When this is done the game speeds up to be playable. No graphical issues, no sound issues, feels good. WHEN those data is fully loaded.. This LAG may reappear in any newly discovered region; takes roughly under a minute to load all those -whatever- . Then it runs smooth. No tweaks needed. Runs out of the box. Gold status due to those strange "LAG until fully loading".