Does GPU acceleration in Illustrator CC still work after disabling 'GPU Preview' and enabling 'CPU Preview' (on a workstation gpu)?

I'm using a workstation graphics card that allows for GPU acceleration in Illustrator CC.

Selecting 'GPU Preview' instead of 'CPU Preview' under the 'View' toolbar in Illustrator CC results in a more choppy experience.

So, I was wondering if GPU acceleration actually improves the performance or not, and whether or not this tier of graphics card benefits me (perhaps I need a higher-tier workstation card?).