As everyone else said, multiple processors does not always = better performance.
Think of this like a business and you're the manager. I come to you and say I can give you a minimal but kick ass staff, or I can give you twice the staff that perform at 50% of the other.
With the kick ass staff they knock the tasks you give them out of the park, but you're constantly having them do different tasks, and there's always something to be done.
With the double staff, they struggle individually with the tasks, and you have to micromanage, splitting 1 job amongst several employees and you will at times be having employees standing around doing nothing even when you're busy, just in case a new task comes around.
So Boss? Which do you choose?