The end date can be set by the scenario if you choose that option. I estimate it is heavier on the CPU than HOI2 but not too much. My Cold War extension will indeed allow you to play Germany till 2010 but the play will probably be sluggish after about 1955 and I don't have many new people for Germany after about 1960. or event support. You'd have to put the people in. However, I do have some of the models. I've set all my scenarios to end in 2025. As for "the AI stopping" the only issue is the expiration date of the AI files.