I did understand, and unfortunately cultural differences usually eliminate humour in comments. So I apologise.
I'm pretty sure that we will experience some slow down in the later phase of the game. However one thing to remember is that the devs have stated their minimum spec goal is a dual-core processor, 1 GB RAM, with directx9 256 MG graphics card. That's not that bad for a modern game, it's much MUCH lower than a lot of new games coming out. But just due to the amount of graphic changes (improvements, roads, cities etc) on the map and the number of units and events in the game, we will definitely experience a slow down in play near the end. It's inevitable with this type of game.