Well the size of the settlement does matter but not to such extend.
I found the exact same settlement type (Epsilon Hydri 6a Kryyst Analysis Lab) on another planet but the framerate was OK, still some stutters but a lot better (45FPS).
Edit : no vsync hard cap to 60 FPS and monitor set to 200hz refresh rate to mitigate the tearing effect. Not tested the fast vsync from nv cc. I don't remember ever seing this option... is it any good for a non gsync monitor ? (only freesync on mine)
I don't have gsync or freesync on my monitor (most likely my next investigation) and my monitor only has 60 Hz. That's why I preferred standard VSync for quite a while, which also caps my frame rates at 60 FPS. But with fast sync I get better results, also mitigates tearing, which I always see when using hard caps. With fast VSync it goes up to 120 FPS now (mostly in space or wherever the environment allows it), no tearing (but on software basis of course which should lead to some performance loss) while still preventing my GPU to go through the roof with something like 300+ FPS. I didn't compare systematically to standard VSync, so you'll have to check for yourself. Maybe I'm making things up, but it feels like an overall performance win to me...
This function is easy to find in the control panel, it's almost down to the bottom. I'm using dedicated settings for Elite (edlaunch.exe, under the tab program settings), so that it doesn't effect other applications. The only downside of not setting it to global is that it always get reset after a driver update.