Thanks Tedric. It is right that I am playing really fast, even so if I do not realize that in process, I could have spend 15-20 turns without any land battle and « big » turns, just organizing, consolidating my empire, planning for the next foe to deal with, but the counterblow of it is that when I'm launched, I can act as a steamroller, blitzing the enemy and at the end reach to the « victory » quickly (as for Rome in this campaign, they were very weak because they never expand beyond Bononia on the east, in less that 20 turns, they have been cooked and I took their last city Akragas. Ironically, this is where I will stop with this campaign like a « beyond the grave » roman vengeance ! Urbs is omnipotent ).
Also I am saving a lot without keeping enough time between two saves. I rarely restart the game during long phases of gameplay, reloading saves instead of get back with a fresh clean memory...
I will take your advices in consideration for my coming Parthian campaign. Sadly though that I will be unable to confront myself with this huge greek military power ! I hope I will see that kind of power again, this was unprecedent to me, maybe because I don't let enough time to the AI to really flourish and manage to establish powerful empires.