Regarding the vGPU profile results, increasing the frame buffer will not increase the performance of the GPU, nor is it sposed to.
Example; if you were playing a game and your configured settings maxed out the frame buffer of your GPU (quality = maximum, resolution = 4k, texture detail = ultra etc etc) then increasing the frame buffer will allow better visual performance (if you were maxing it out). But the performance of the GPU will still be the same. It’s still running at the same speed, but the game will play a lot more smoothly. The same is true of professional graphics, the higher the settings, the more monitors you add into the system, the more frame buffer you will need to deliver the desired experience.
I wrote a very basic post on benchmarking and some basic system tuning options here: https://gridforums.nvidia.com/default/topic/993/grid-vgpu-benchmarks/maximising-performance-using-up-to-date-drivers-and-basic-system-tuning/
It’s mainly around Operating System power settings and driver versions, although there are hardware power settings, BIOS configurations (including cooling policies) and hypervisor power settings to consider as well.
As I said, it’s very basic, more directed at newcomers to the GPU world. However, one of the things I touch on in there, is that once you’ve bought your hardware, your chances of being able to increase its performance are limited, and unfortunately, increasing frame buffer (in the context you are testing with) is not one of them. You’re into software refinement, optimizations and overall system tuning to squeeze a bit more performance out.
If you want more performance, you either need to purchase a faster GPU, or you’re then into the world of overclocking (in that case, check out the GeForce forum) but this is an unlikely option, considering you have a K2 :-)
As Simon mentions above, check out SpecviewPerf for more relevant, complete system benchmarks.
Regarding the performance difference between Passthrough and vGPU, with the K1 / K2 GPUs, there were some features that were only available through Passthrough, and not vGPU. I don’t have a complete list of these, but I believe CUDA used to be one of them. Maybe a lack of these settings is contributing to the difference in performance?