Same environment (Radeon HD 7850, i7-4770, 16GB, SSD), same plan.
During rendering of a walkthrough:
X8:
CPU 30%
GPU 15-20%
X9:
CPU 15%
GPU 90-95%
Rendering a walkthrough for that plan under X9 takes 8-9 times what it took under X8. Granted, overall 3D performance has greatly improved with X9, but this situation forces me to do renderings while I'm busy on something else, then you loose that work flow .
I also understand that there are some new parameters (bloom, occlusion...) which make performance comparisons more difficult. Given the augmented usage of the GPU under X9, I know my aging video card is begging for an upgrade.
None the less, I'm curious if anybody else has similar or dissimilar experiences to share about walkthrough rendering under X9.