OK I have reinstalled 64 bit and was having the same problems.
I realised it may have something to do with the laptop running on battery power so I plugged in the power supply and the performance meter dropped back to the left straight away.
I then read this thread regarding power schemes…
After reading that thread I decided to turn off the Cubase power management and went into the advanced power options of Windows 8 and made each of the settings for battery/plugged in identical for testing purposes.
Screen brightness and CPU performance were the same as was everything else.
However when I pull the plug on the Laptop the screen dims and Cubase performance goes out the window again.
I went back to power settings and my edited settings were still as I set them. They were unchanged…
Not to be confused with the abovementioned thread where Cubase will change them.
I have Steinberg Audio Power Scheme OFF!
Anyone have any ideas what’s going on here?
edit OK I poked around in the ASUS programs folder and started power4gear.exe as admin.
You can change the settings manually but still no effect!
The trick is to pull the plug on the computer, the icon jumps from performance mode to battery saver at the top then simply click back to performance with the computer unplugged and the settings will stick…
Finger crossed I can now get around to enjoying my new computer and C7. 
Thanks everyone!