first mission Heart of Gold
So I finished the original campaign (wich was great btw!) and just started the Heart of Gold expac. During the first mission the longer I play, the laggier it becomes, framerate drops into singledigit, and in the end the game just freezes (permanent) and I have to exit the game through the task manager.
The game is now running on a brand new HD
the rest of the setup is the same: i5 4570, 8 Gb RAM, MSI 970 4 Gb