I think the most important question to ask before even looking at the game performance is if the game is any good? In this case, it looks like one of the worst Anno games ever made, with the game getting mediocre user reviews, criticizing it for being too easy and dumbed down. Since there is no multi-player, and the game is to easy, the re-playability factor is basically non-existent.
"Save your money. This one is barely worth $25. It's good for one playthrough only and this is not an angry exaggeration. You play the tutorial only to find out that the tutorial is the entire game and that's all there is to the game. You just play it over and over again, but it's the same every time. The goal is to build a generator on the moon. Since there's nothing to stop you from doing that and there's no more randomly generated maps, after you've done it once, you've experienced everything the game has to offer. No more challenges, scenarios, multiplayer, factions, trade, or real combat. It's Anno, with everything that makes Anno sucked out of it."
The hardcore Anno gamers are giving this game huge thumbs down.
http://store.steampowered.com/app/375910/
That means to start with save you $40-60 and get something worth buying like Fallout 4, The Witcher 3, Dying Light, Mad Max, Rainbox 6 Siege, MGS V, GTA V, etc. With so many games to play, unless you are swimming in cash
and free time to play every new game that comes out, even if this game ran at 144 FPS on integrated graphics, is it actually any good and worth purchasing? The consensus seems to be no. Save your $ and pick it up for $5 when it's patched. At least when it's $5 you won't feel bad about its poor performance or lack of challenge/re-playability factor.
Of course this doesn't change the poor performance of GCN and Kepler relative to Maxwell, and it would be interesting to see how GCN/Kepler fare in this game over time as it gets patched and NV/AMD improve their drivers. I wouldn't be surprised if AMD's drivers for this game are basically not optimized at all. It's hard to explain how a GTX960 is on the heels of an R9 390/390X.