Memory buffer upgrade 
If anyone knows more about it, there should be a discussion of the memory buffer upgrade Why for example does doubling the memory result is more than double (from 28 to 68) the number of shots in NEF (RAW) (12-bit lossless compressed mode FX mode, but no increase at all in small JPGs (it remains at 130). I suspect this is related to the fact that small files can be shited to main memory at a rate close to the maximum frame rate of the camera, but much larger files can't be transfered as quickly. But a more detailed explanation would be useful.