all the major gravitational bodies in any rotating system will eventually align along a central axis due to centrifugal forces. this is equally true of solar systems with planets and spiral galaxies with stars. it makes perfect sense, from a physical perspective, for all the grav wells to be in the same plane.
the other issue is simply one of usability and presentation to the human player. if the objects had greater z axis separation in would be harder to keep track of things. in my opinion that would be a bad outcome and would lead to a more confusing game without much of a gain in visual attractiveness.
I am no developer, okie? So my comments may be off, but to my way of thinking, the slight rotation already in game for the planets could be used, without any calculations of any kind to the solar system. Have the solar system as a whole simply rotate using the same algorithm that the planet uses. The calculation is static, the movement extremely slow, but also perceptible. That to me would allow for singular maps to rotate about the axis of the skybox, which with a small introduction of some location specific anomolies, a bright three point star in one direction, the cloud layers in another, a blackened field of space devoid of stars in another. All these could be minor drawings added to the skybox, and the movement of the system about them small, but again perceptible by the player.
We dont have to have dozens or hundreds of calculations added, and we dont have to have to continually re-calculate. Each piece could be set to move on its own, this would be for multiple star maps. Or even the same for planets in a star system. Each moving about the core of the star.
Each piece then, planets about the star, the system rotation, and multiple star rotations could add only a handful of embedded and static code for them to follow.
This means visually the system becomes more interesting, more interactive, if phase lanes change according to what planet is nearest, it also means more fun, more strategy and not necessarily more code-crunching and memory eating threads to calculate. As i said i am no coder, but it would probably eat more memory to start another browser window than to set up the spin mechanisms for the game.
If this is not the case, then please explain how it will in fact make the game unplayable.
Just my two cents, not flaming, simply trying to express that i think this is possible without taking the game out of the low hardware threshold. Anyway, take care and keep modding!!
-Teal