They are not fast routes but you can go from north to the south of the galaxy. My solution was create hidden trade routes around the galaxy, in the borders. First with a galaxy where the AI, specially the CIS AI started with planets far away some from the others, I needed improve it. There two curious things that I have made the past days. Mostly improving the gameplay and the AI behaviour.
It is a bit long by the amount of changes. Well, another week and I continue mostly improving the last Insurrection GC.