Forcing The integrated Makes Everything Work Just fine! stable 60 fps +-
The Thing is using the integrated doesn't allow you to use a secondary display, and of course GPU power is lost...
I guess this is a Mavericks Issue or Nvidia Driver Issue.

So they blame Software Developers now....my best suggestion here would be to get in touch with the developers of the software. They might have more information on if the issue has been reported, and if there’s a way to get their program to run properly on Mavericks (i.e. in this case, get higher FPS)
That's almost funny.They might have more information on if (...) there’s a way to get their program to run properly on Mavericks
I'm sorry but I won't be able to send the hardware Because of TAX issues in my country.Joris wrote: If you'd like, you could send it to us (on our cost) so we can take a look? Although I can't promise that that will give any immediate results.
So far With the latest 10.9.3 Beta No improvements at all...Mavericks 10.9.3, which is still in beta, is going to have changes to graphics drivers. The main purpose is to expand support for 4K but I imagine there will be performance gains as well. DO NOT be tempted to chase down a pre-release version because there could be new problems introduced that make your system even less reliable. There are also no guarantees that the final 10.9.3 release will make things any better. Keep your fingers crossed.