It is hard to identify the scoring formula with certainty, although I have been working on it for some time. The best I can do is ~967/world in score. If you look at my top three scores in the small map catagories: 135450 on a medium (140 worlds), 97650 on a small (100 worlds), and 74200 on a tiny (71 worlds) they all cluster creepily close to the same 967 (or 967.5) per world. I'm still trying to figure out what I can do to try and get over 1,000 per world, but I'm starting to run out of ideas.
Well, I am certain the ~967 per world barrier can be broken; provided that my computer doesn't melt down, I will submit a demonstration score soon. But the methodology is really dumb -- just spam 1 attack/1 defense (with Armor Plating, lol) tiny ships and have them all rally to a 16 military starbase cluster with all the ship assist upgrades. They require only 1 maintenance so you can do this practically forever; you're constrained more by the speed of your computer than the game rules. The only things I actually do during a turn now are rush-buy a few larger ships to keep my treasury below 20k to protect my econ score, and occasionally blow up the ships the poor Altarian AI has built (but I'm now trying to keep that to a minimum since it can take 10-15 seconds for the computer to respond when I click on a ship); average ~1 minute/turn. Then I have to wait more than 5 minutes before I'm given my next turn...
I'm not even exploiting this to the max; ~60% of my planets don't have a starport (just Stock Markets and 2 farms, and a single VR center if PQ < 11 so I can have 18b population across the board).