Slow Shutter NR on Km

Have been using my camera a lot lately indoors with the fab 35mm plastic. Still sometimes I require the flash as I usually only allow the camera to hit iso400.

Then I stumbled across the NR settings, that I had probably set and left alone since I bought the camera.
I know the high ISO one probably loses some sharpness, hence set to off although I do not know what they classify as high.
The setting I have never played with is the Slow Shutter NR. Again I am not sure how slow the shutter needs to be before this is used, and whether it has a detrimental effect on the image like the other NR setting?


Just bought a Olympus Tough compact for messing around near/in the water. Now my noise concerns on the Km are nothing compared to that!