GPU-based, currently 3dsmax only
There is not so much info since it is still very new
http://www.fstormrender.com/
Yeah 5000 samples for a noisy fork looks impressive…
At the moment though, the render engine itself may be quite fast in placing samples onto the image because of the tiny size of the kernel (judging from the small amount of features).
Wait until it gets to the stage of being fully featured and see how much slower it becomes barring new optimizations (the GPU tends to become a very tricky thing to code for once the application becomes complex).