No, though it has been observed the AI does less well in multistar maps, especially ones where they spawn in a system without other players.

As Goafan said, the AI doesn't play well on maps with large distances between colonizable gravity wells; multistar maps are the most common case, but the AI will display the same problems on a single-star map if you, for example, place a very good planet incredibly far away from all other gravity wells. It is important to note that the AI cares about distance only: for example, even if you have a wormhole next to said incredibly far away planet so that players could travel to instantaneously with wormhole tech, the AI will ignore the wormhole, as it sees the large distance between the two wormholes, not the instantaneous travel time between them; quite an odd oversight by the developers, if you ask me. If you still want multi-star maps, you can make sure the systems are as close to each other as possible (overlap causes displacement in the z direction, which actually makes trips longer, since gravity wells are cylinders, not spheres).

One possible work-around is to make gravity wells essentially touch each other, but reduce interstellar travel time via modding. The AI will see the gravity wells that are extremely close to each other and will be less picky about what planets it visits, but the actual travel time between gravity wells remains the same as it was in vanilla.

Be careful about putting planets so close together so as to make grav. wells touching.  The game engine loads all resources at each planet that is physically visible by the camera.  You can induce alot of load on the game if it is loading more than one or two planets' gravity wells worth of stuff at a single time.

This may or may not apply, but in 7ds we use very large planets and had to space our planets/galaxies far apart such that when you zoom inon a planet, only that one planet is visible (the adjacent ones are visible as icons).

To change the distance between planets/galaxies in general, the easiest way to to go into each galaxy file and increase or reduce the "meterspergalaxyunit" value. increasing it spreads things further out, decreasing it beings planets/galaxies closer together.  As others have said, be sure to adjust base warp speed (found in each player entity file) accordingly so you don't get super instantaneous travel or incredibly long travel times.

No i think the distance to render is hardcoded.

Ahh, interesting I never noticed those in the gameplay constants file!   You could try messing with those and seeing what happens, ive never modified those.