Obviously there needs to a cost to maintain your fleet, but I think it should be a set amount per upgrade you research, rather than a percentage.
I mean, yes, it makes sense earlier on when you have a small fleet & limited income, but if you, like me, like to drag your games out for as long as you can over large maps, I'm currently in my 23 hour of my current game on a map with nearly 2000 planets, it starts to get a bit silly.
Alright, you probably don't play like I do, but still, when you hit you current limit for ships & stay at that amount whilst colonising more planets, why should the cost to maintain your fleet also rise?
You're fleet isn't growing, the cost shouldn't.
In my current game I'm paying 200 cr/s to maintain my fleet, when earlier, with exactly the same ships it was costing only 75 cr/s, or something similar.
Something ain't right here.
Methinks when you research an upgrade for your fleet capacity instead of the cost rising from say 50% to 60% it should be more like 45 cr/s to 55 cr/s, or whatever seems more reasonable.
It makes no sense that the maximum ships you can have should be capped but the maximum costs aren't.
It would also stop people from spamming capacity upgrades, as doing so could quite easily bankrupt you if you don't have the infrastructure to support your fleet.
Planets would also become a lot more valuable too, as your enemy could take just enough planets to drop you into negative income & starve you to death.