>
>May slow down the memory buffer a little bit, but so far it
>has been effective for me when shooting JPEGs up to ISO 1600.
>Note that it won't work when you're shooting RAW images,
>though ...

When doing long exposures, turning this on as well as long exposure NR kills any hot pixels that the sensor may have, even in RAW, so it does make a small difference when shooting RAW. Generally though, if you're using RAW you should just kill the noise manually.