Looking for some advice, I've finally got around to playing a big map long enough to reach the point where ungodly sized fleets are pounding on each other on a regular basis, and I've hit a roadblock. Its a multi-star system, 5 total. My problem is that My opponents (all hard ai) just keep running circles around me avoiding combat. If I ignore any one fleet for too long (three different opponents, although only two are actively engaged with me) then they easily knock down a single planet, sometimes two (all my border worlds are full on tactical defenses, so it takes some time).
Just can't figure out how to break this impass. I've been able to strike into their border worlds and take down a few, but I never get the time to solidify my hold. If I split my big fleets (two, usually running circles with the other two big fleets the AIs have out there) I end up getting some conflict but then I take so many losses I can't exploit the weakness the AI has for that short period of time, we both end up in a build spiral that culminates in the exact same situation. Been like this in the game I'm playing for two hours.
I haven't had this problem on my single-star map as the borders are a bit more defined, whereas the multi-star map has incursions everywhere since you can't efffectively blockade the star itself.
Just for Reference, I'm Vasari against another Vasari and an Advent (fourth is an Advent as well, but he's locked down with Pirates constantly).