Low graphics performance

Hello,
this has been going on for quiet too long and cannot be a simple driver issue: I've got a MBPr 15" with 8GB of RAM and the GT650m and games still perform poorly. Using Bootcamp on a 55GB partition, 5GB still free, pagefile enabled.

e.g. Dishonored runs laggy (10-50fps with micro lags!) at 1600x1050 normal compared to the 1080p high of this guy with 16GB http://www.youtube.com/watch?v=NsZ46faXqCs
It cannot be just the RAM...

I noticed this in a ot of games where my machine would perform way worse then in fps tests on the net.
Any ideas?

 

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