So I'm wondering, in the light of this example, what can take power to make those AI turns. Eventhough even in my own turn, in Old World, I saw lags all over the place in inability to play due to camera/game freezes. They say they made the minimal for a ~2014 computer, but I fail to see what such 4X could do more than Civ to be unable to run ok on slower ones.
In other words : I couldn't witness, because my inability to play, what could demand more powerful computers to play that game. Anyone ?
One difference is that Old World is memory-hungry, and that was more true before they optimized it some time in the latter part of 2022, IIRC. I had 20 GB of RAM in my desktop at the time, and playing extra-large maps such as the Middle East + Persia map (which shipped with the game), that was not enough memory, which slowed everything down drastically compared to when playing on a Standard size map (both the smoothness of camera/game movement during my turn, as you describe, and AI turn times). Much as try to play Huge Civ IV maps on my Pentium IV with 512 MB of RAM slowed things down tremendously in late 2006. Going up to 32 GB of RAM helped Old World a lot, and doubling to 1 GB of RAM helped Civ IV a lot.
So if you are reading this and thinking "I have 8 GB or 16 GB, and I last played Old World in 2021/2022" - that's probably it. It may be better today, if I'd started playing 6 months later I probably wouldn't have needed to upgrade as the optimizations were considerable.
Aside from that, I had no complaints on my desktop, which was hardly a barn-burner by that point. I still had a decent graphics card, a Radeon RX 480 8 GB from 2016, I think I played on Medium? Relatively ancient midrange CPU (Core i5 2500K, purchased in 2011). I can't really say whether Civ VI ran better as I didn't play much of VI until I'd bought my new laptop at the end of 2022.
As for the
why - likely a combination of a small studio not having had the time/expertise on how to optimize upfront, and using the fairly general-purpose Unity engine for Old World. Unity is popular as it makes development of games easier and thus can mean the difference between the game being completed or not, but it has somewhat of a reputation for being the engine behind un-optimized games. How much of that is on the engine itself being inefficient, versus it being popular among developers who have an idea for a game but not a lot of experiencing optimizing, I couldn't tell you. Wouldn't be surprised if it's some of A, some of B. As far as I know, Civilization (except IV) uses its own engine, so Firaxis can optimize to their heart's content if they have the time and budget to do so.
I will note that the Old World developers have been reliable about updates over the years, and often swing by the Old World section of CivFanatics and chime in to discussions; some of them used to be Civ modders at CivFanatics or Apolyton. You may recognize their names as well!