After playing a few hours, FPS drops from 40 to 5FPS

not bad… so again a driver stuff related to the gpu… as mentioned the 30% cpu may be one core ( check single core view ) and this can you may be only avoid with lower some settings ( may be LOD ).

PS: this happens if users duplicate here single issue into different topics… the discussion is now more like a spider-net: Worse Performance - SU7 - FPS - #261 by Radioactivegoos