That's funny regarding Montero. God I hope that's not the case in real life. As far as selecting countries goes, the more you select, the slower the game will run. But, as you saw, you will have a larger variety of players available to play with in those leagues. Plus you yourself can manage there, as well, if you wish. But if it is slowing down too much, I think that playing with fewer players does not present that much less of a game (you won't notice the fewer players that much).