As no one else has answered yet, I have a Macbook Air, latest generation.
You have to be very patient with Aperture and D800 photos. The tasks I checked randomly take roughly twice as long time as for D300 photos. I more and more appreciate the DX option.
For FX D800 photos I tend to browse them with View NX instead, which is much quicker. And then I'm just a mouseclick away from Capture NX from more serious editing.
Don't have a D800, yet.
But I have worked with 100+ MB TIFF from scanned slides for years. And that includes working with a 2006 MBP with 2 GB of RAM.
Others will add refinements but there are several stress points in the Aperture workflow that may show the impact of larger files:
-- Basic file handling. Importing, exporting, copying, etc. may all be a bit slower depending on your HD and bus speeds, etc.
-- Browsing and similar processes should show little or no difference once all of your thumbs are rendered.
-- Loading images will be slower, especially zooming to full resolution. This will be driven by two different factors - the size of the file and the processing power of your GPU.
-- Similarly, computationally intensive Adjusting, like Shadows and Sharpening will take longer to render. Other simple Adjustments, like white balance, usually show no slow down.
The usual rules apply:
-- As much RAM as you can afford and, if you see bad slowdowns, shut off other programs. A small refinement is to avoid switching from one image to another when Adjusting as this requires the new image to be read into RAM.
-- Keep your Library on your fastest, emptiest HD. (Consider relocating your Masters onto another HD to achieve this.)
There is one unexpected side effect to D800 RAW files - if you use plug-ins that make TIFF, a colleague reports that these run to 200 MB each. Ouch!