The lag or stuttering starts sometimes from the get go. Perhaps it is worth noting some other facts about my set up: I installed this some time ago and it seemed to help, a bit. I like to play that way and it seems better for my FPS, too. I tend to keep a birds eye view of things and rarely zoom in close. For some reason many of my residential buildings were showing red 0/0 (zero) households, despite demand for more, then suddenly they began to fill up fast over a few real time days of playing with loads of activity and that's when FPS/stutter was more noticeable. But at 425k there seems less people and vehicles around than there were previously during heavy waves of incoming citizens. On my current city when pop was around 150k is was very slow, but feels the same if not a bit better now at 425k. There is truth in that the higher the pop the slower things get, but for me it seems more a case of the more cims and vehicles out and about the slower it gets. Next time I'll just buy a system capable of more RAM, but for now my laptop is maxed so I just live with it. My laptop stats are very close to those of the OP and my FPS is about the same.
