It should work quickly. Can you describe your situation/problem in more detail?
It's slow for me in two ways. The first is simply the mechanical process of copying and pasting. In that respect I'm probably spoiled by the nice way that ACR allows me to just click in settings when I have several files opened in the ACR window.
The more curious delay is the time NX takes to apply the pasted settings. To my mind the program is only changing a little bit of text and re-writing the thumbnail preview, but it takes 10-15 seconds, about the amount of time I'm accustomed to waiting for a whole file conversion.
I've seen a reference claiming that the process is faster if I make all my adjustments in New Steps, rather than Base Adjustments. True?