Quagga
Former Dictator
Finally Universal Suffrage, I can just disable it for cash rushing, or maybe have it only cash rush essential stuff - granary, lighthouse, workboat.
I think it's better that it just doesn't cash rush at all. By the time one is running US, speeding any of the builds suggested probably isn't critical. Better to have the player intervene than have the treasury depleted at a critical moment.
Another thought: Never use more than, say, 25% of the available treasury to complete a building. No, I guess that won't work either. The first city will use 25%, the second 25% of what's left...