Nikon Coolpix 5400 and Noise Reduction

I just purchased a Coolpix 5400 got it last Saturday. One peculiarity I
noticed--the NR icon for "noise reduction" is always on even at higher
shutter speeds when it shouldn't be necessary. I thought it only engaged
when it was necessary.
On the other hand my CP5700 only displays the NR at slow shutter speeds
(like 1/8 second or slower) even if NR is enabled in the menus.

I did just try out the CP5400 and it does seem to slow down with NR enabled
in the menus even at fast shutter speeds. This would seem to be a big
disadvantage vs the 5700 which I can leave in NR permanently rather than
having to turn it off for daytime and turn it back on for night-time.

What have any of the rest of you noticed?

LRH