Today was the first time I saw the Super Dominator corvettes, and the sheer number of them was crashing my game. I don't think this is because of a game issue, but rather just that I've got only 512MB of RAM and I'm playing on a noteboook PC.
Anyway, the Drengin were on a pretty dopey intelligence setting so I created a large ship with lots of weapons and a bit of defense + the Super Warrior ability and declared war to take out all those corvettes. The game ran much smoother after that.
And I got an uber ship from killing all those corvettes