I'm not familiar with the Unity engine, it's strengths, weaknesses, limitations, ect. But if at all possible part and environment culling (view-frustum, back-face, and occlusion culling) should be added into the game with toggleable settings for each type of culling.
There is a slight problem with this game and its performance correlating to craft part count and size.
You could have a craft with a 2000 part count and small relatively small profile run pretty optimally even with high graphics and physics.
However you could run another craft with the same 2000 part count or less for that matter but with a larger profile and performance will drop quite substantially especially if you are working with interiors.
I feel like this could partially be solved by being able to cull parts that aren't actively being displayed on screen as well as being able to cull parts of your surrounding area so the engine isn't having to render out everything around you.
This would be very useful especially for mobile users but also for PC's with processors that can't necessarily deal with heavy loads and in general will help with creative freedom/gameplay as another issue is being close to another craft in game causes massive FPS drops.
Not sure if the game already addresses this to an extent but if not it would be very helpful in general.
@Pedro Thank you for the info. Is there any way to implement other forms of culling or have devs experimented with it and have found it to not make much of a difference?