Hello m0ns7err,
Changing the Operating System to a 32 bit version should not make a different on game performance since this is related to System (hardware horsepower) performance.
I have checked this on a system similar to yours and I was not able to replicate this performance issue. Remember that when a processor has been designed for mobile platforms, it means the CPU processing power will be lower than a desktop platform due to the low voltage and power consumption design.
So I would say problem is with the system horsepower rather than the graphics controller.
I hope this helps you.
Kevin M
