Soldato
It appears in actual use the LR CC performance is no faster than LR 5.
Yes it now uses the GPU rather than the CPU but it's not any quicker because of the switch.
I've found the same in reality, although I still feel there is an improvement over LR5.
It is worth trying it without the GPU acceleration turned on though. On my 13" Macbook Pro Retina I think it is slightly slicker without it on than with.
I assume the graphics model has a difference though. My Windows desktop only has a GTX 560 Ti too. Would be nice to try it with something newer.