Pillar cost currently scales with the game speed, but this is wrong, and let me explain why. The math is simple. At faster game speeds all the stuff costs less to produce (research and city growth cost less too), and because of this the game ends much earlier. And when the cost of all the things is decreased by two times, then the game will end exactly twice as fast. Consequently at slower speeds everything requires more supplies.



Now let's focus on something, that produces supplies, like Empire Mint. It produces 5 Dust per turn (let's pretend there is no +15% Dust bonus) and costs 75 production in normal game. Thus in normal game, which typically lasts about 300 turns, it would produce a total of 1500 Dust. At the same time in fast game it would produce only 750 Dust, because the game would end in 150 turns, and Empire Mint would cost 38 Production. Thus the production cost is twice as low, but it also produces half that much Supplies during the game.



On the other hand the upkeep cost isn't changed for anything on any game speeds. This can also be explained quite easily. Let's take Mill Foundry for example. At normal speed it's total upkeep would cost 300 Dust on it's upkeep (1 Dust upkeep, 300 turns), if it has been built early. At fast speed the upkeep is going to cost half as much. It would cost only 150 Dust. So, as you can see, no alterations needed here, since upkeep cost scales with game speed by itself.



Same goes for different buffs, and the developers do understand this. For example they made Empire Plan last two times less on Fast speed, but it costs 2 times less too, thus effectively being unchanged. Same goes to Luxury buffs. The duration is halved, but the extraction is doubled, which balances it out completely.



But the pillar cost does scale with game speed for whatever reason, though it is effectively a buff too, or something with upkeep only - treat it whatever you like. Now let's count once again. At a cost of 40 gold per 10 turns, pillar effectively costs 4 gold per turn at normal speed, so it would cost 1200 Dust to keep it active for the entire game. At fast speed it costs 2 gold per turn plus the game lasts less, thus permanent pillar would cost only 300 gold. So the cost is 4 times as low, not 2 times. This makes pillars OP at fast speed and practically useless at lower speeds, because it cost grows as quickly as it drops.