If by 1:1 Preview, you mean the stage, after importing files, when you click on one and then bring it up to 100%, then my D800 lossless compressed take about 5 seconds while the screen says "Loading".. (slightly faster processor than yours and 16Gb but files on external normal HD, no SSD)
For me that is OK as I work with two 27" Dell monitors and the 100% will be on the 2nd screen so I can still be working on the normal sized image on Screen 1 while it loads.