I don't know if you still have this issue, but maybe what worked for me will work for you. I had it all working perfectly on my Windows 7, Core I7 machine. Then I started fiddling around with audio settings to see if I could bypass Guitarport and go straight into Gearbox using a Rocksmith Real Tone cable. I couldn't. Then I plugged Guitarport back in, I had horrible latency that wasn't there before, like a half-second delay. I spent two hours trying everything I could think of--adjusting system audio setting, soundcard settings, Gearbox settings, restarting everything. Nothing worked. Finally I launched Line 6 Monkey and saw that there was a firmware update available for the Guitarport. I installed it...latency gone.