http://www.bladeandsouldojo.com/topic/126486-switching-graphic-control/
This is a two part step to maximize performance and to create more stable FPS. This mitigates FPS issues but doesn't completely remove them.
Part 1:
Open nVidia Control Panel
Click the "Adjust image settings with preview" tab under 3D Settings section
On the right window you will see "Use the advanced 3D image settings" bubble (Check this bubble)
Click "Take me there" and you will see Global Settings. Adjust this until you get the best performance for your PC
Ensure the programs you are running is utilizing Global Settings not it's own settings
Part 2:
Go to Configure Surround,
PhysX
On right panel you will see "
PhysX settings"
Set the Processor to run your nVidia GeForce card instead of CPU
The above should help improve FPS by making it more stable and will work for all games not just Blade & Soul. This method only works on nVidia cards so not sure the process for AMD cards.