Boosts
This page holds the boosts Double Time(10m default), Infinite Double Time (Paid), Fast Forward 10m, and Fast Forward 60m. These boosts hastens the rate at which you gain currency.
Double Time (10m default)
This boost doubles the rate at which you gain money (if you are gaining 1m/sec, you will gain 2m/sec with the boost activated). This is a very helpful feature to the game especially when you are actively playing it as it only runs while the game is open. Meaning offline earnings through the bank are not affected by this boost.
The game upgrade "Atomic Timekeeping" extends the 10 minute boost by a 6 minute extension per upgrade. Although the upgrade itself is expensive in bux.
Infinite Double Time
This is a permanent version of the Double Time boost. Although you have to pay aroung $6 USD for it.
Fast Forward
These two boosts both, as the name suggests, moves the time forward. Their only main difference is the amount of time moved and for the amount they cost (10 minutes for 50 bux vs. 60 minutes for 250 Bux).
Although tempting, it isn't really a good idea to spend bux for this. For one, the amount asked (50 & 250) is a Bit steep. It is better saved and then spent on much more meaningful, permanent upgrades.
Another reason is that if you play your City for 10 minutes / 60 minutes, your income would be far greater in the long run if you spent Building on empty lots, upgrading buildings, and purchasing upgrades.