To evaluate performance and compare a system natively vs virtualized+passthrough (and to some other solutions), I ran a couple of benchmarks on each.
For some reason, my windows 7 guest os seems to operate in two different performance modes. In "mode 1", furmark (a benchmark to test gpu, with 1080p preset) will result in about 3070 points/51fps, "mode 2" results in 2680 points/44fps (also 1080p preset). As long as the vm is up, results will always be close to the ones mentioned (+/- few points). The only thing I do to "switch" those "modes" is to reboot the vm, and I will never know in which mode I am in until I run a benchmark and check the result.
Furmark here is just an example, the behavior/difference exists in other benchmarks/settings too.
Host machine:
ESXi 5.5.0 update 2
Intel i7 4790k
ASRock Z97 Pro 4
AMD R9 280
Guest:
Win7 Pro with recent updates and drivers, AMD R9 280 graphics card is being passed through.
For anyone interested, furmark on native windows 7 will also be around 3070 points.
I am not an expert in anything VMWare and am looking forward to anyones input to shed light on the situation here.
So.. what do you think is going on?