I´m talking about how peace deals are handled by the AI.
The classic example - suppose you have 5k military strength and they 15k (Let´s suppose the AI also has larger GDP, through that doesn´t really matter dor this example). Despite all the AI shortcomings it could probably crush the player easily (specially because from my experience, at least in early game if the AI has larger military score it means one thing - it got more abandoned ships than you, and we all know what happens when a cruiser with phaser lances or titan beams engages one of yours with crappy blasters).
What happens, however? If you declare war and get a colony ot two before the AI can react, if you ask peace, they will usually accept AND for a small amount of cash. It´s totally silly, it would be as if the US accepted peace with Japan after Pearl Harbour and conquering the Phillipines. Was the battle lost? Yes. Is the war lost? Definitedly NO. As it is, it´s too easy to dismantle an empire little by little, by doing blitz wars and a fast peace.
So, for considering peace costs (and as a matter of fact, even if it should accept peace), I suggest that military strength value and war weariness should be the critical factors, and not a recent victory for the player as it is now. Want peace? Kill some ships and make them tired of war until you got the upper hand. It would also be an incentive to play governments with lower war weariness (because honestly, despotism and feudalism only handicap the player/AI).