I'm creating random planets from an array, so I guess it has to be done through script. There's no mesh in the editor for every planet, I'm just spawning the same sphere and then changing the texture... you know, procedural things.
My specs: Windows 10 - Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz - 16 Gb ram DDR4 - NVIDIA GeForce GTX 960M 4 Gb