Fleets burn something now
Crossing the void costs energy, and you choose how fast to do it. Slowing down is cheaper — which makes distance a decision instead of a wait.
Distance used to cost you nothing but patience. A fleet left, a timer ran, and the only question was whether you were willing to wait. That is a countdown, not a decision.
The crossing has a price
Moving a fleet now burns energy, scaled to what you are moving and how far. Your composer tells you the bill before you commit, not after — a launch that empties a world is a mistake you should be able to see coming.
What this changes is what a big fleet means. Mass was free to move and is not any more: sending everything, everywhere, all the time is now a choice you pay for, and the cheap raid on a close neighbour is a genuinely different proposition from the punitive expedition across a galaxy.
And you set the speed
A slider at the end of the launch, with the trade-off in front of you: go slower and the crossing costs less fuel. Not proportionally less — the curve bends, so easing off a little saves more than you would guess and crawling saves less than you would hope.
It gives the same fleet two honest uses. Run it hot when the timing is the point — a raid that has to land before a defender logs in. Run it cold when it is a supply convoy and nobody is counting minutes.
The point is not the arithmetic. It is that “when will it arrive” and “what will it cost me” are now two separate questions, and you answer both.