Prime Time is a limited time Event that allows members to purchase gold with an additional percentage added on.
The most comon is the 50% Prime Time that happens for all members across the server at the one time. An additional 50% of extra gold is added to your gold purchase while this Event is active.
The 100% Prime Time is extremely rare and only occurs on individual farms. You receive an additional 100% extra gold when you make a gold purchase while this Event is active.