Its fast:
http://anandtech.com/show/7335/the-iphone-5s-review/5
I know the OSes are different but it is really doing well against the Z3770,which Intel has just launched for tablets a few days ago!!
That is only for the phone version too, just imagine the tablet model??
If this is any indication of the performance of the newer 64 bit ARM cores,we are going to have an interesting 2015!!