Indeed it is a dual card setup, but have set it to use the Nvidia GPU already, tried to fiddle with settings and so on. I have experienced some lag in very large files before, but since latest windows update the lag is just simply unbarable. Will try to copy everything into a new file, see if it works.
I have made a clean install of Rhino 5 and rebooted computer several times since upgrading to latest nvidia drivers.
Nvidia also displays that Video memory is limited to 64 MB.
And task manager shows that only 5-12% of the GPU is used. WHY?!?!