Since the speeding of builders have been ruled out, how about this.
I know there is a formula for how much time can be saved by gemming upgrades. Let's say you have an upgrade that costs 1000 gems to complete, but you only have 800 on hand. Let us use 800 gems worth of the upgrade, dropping the upgrade time from 7 days to somewhere closer to one. It should not be that hard to implement as the formula is already built into the system and it may increase the amount of gems spent.
