I use Bryce and Vue so I have no need for Firefly. But even the Poser 4 renderer in Poser 5 is so much slower than Poser 4 or Propack. Propack is slightly slower than Poser 4. And it's not just the renderer, the interface is more sluggish as well. At one point I had decided to use Poser 5 because of the better library management. I gave it up and went back to Propack because of the speed issue.