Now, before we begin, I must confess-I am no technology expert. However I happened to stumble upon this obscure website: http://www.dsogaming.com/pc-performance-anolyses/crysis-3-pc-performance-anolysis/
This anolysis concludes that Crysis 3's physics are CPU dependant, which is rather odd, due to the fact Crysis possesses many assets, such as each individual blade of grass, to have its physics calculated. To my understanding, by choosing the CPU to perform such tasks, you are essentially going against a CPUs very nature (As CPUs, vaguely speaking, typically perform one calculation at a time, which is different to the GPU). This is most likely the reason why many have been experiencing performance issues, even with high-end GPU's.
What can Crytek do? Well...it would be nice if they made the physics GPU dependant instead. I can not say how much work it would take, though I would assume it would take much.
Now of course, my theory is based of the article which means, if the article is wrong-then I am also wrong. If we come to the conclusion that the article and I are wrong-then feel free to shut down this thread.
Thanks.