Zombie69 said:you'll only need 14 + 15 + 16 = 45 food in order to produce 90 hammers. Well worth it.
It was 13+15+16, because growing from 5 to 6, left 15 food in your food box.
Zombie69 said:Well worth it.
It depends on what tile was the slave working on. If they were all working on forest plain, you're losing 6 hammer for 5 turn (turn required to accumulate 13 food from 3 surplus), plus 4*7+2*15 = 88 hammer, which is good since you get the product now instead of 90 hammer later. If it was mined grass tiles, then it may be better to build slowly.
A spiritual leader can synchronize slave rush with certain civic to gain more. Since each slave worth 37 hammer when rushing building under certain civic (forgot the name), then you can temporary swap to it to rush some building in some city for awhile, then swap back to grow back the city.