There's no forum that this really fits in, but it is related to D800 file sizes, so I'll stick it here in case it's of use to someone else.
I've always used IrfanView as a quick view function for just flicking through folders of images. I'm not sure about its colour accuracy, but for everything else it can't be beaten IMHO.
When I first got the D800, it occurred to me that IrfanView was a little slow in loading .NEFs, taking 3-4 seconds per image. My machine is pretty fast (Win7 64bit, Quad core i7, 12gb RAM, GeForce 9600GT card)so I didn't think hardware was a problem, although the graphics card is definitely not considered anywhere near top end any longer.
Anyway, I was looking around for something else and downloaded the free trial of FastPictureViewer. As it happens, and rather annoyingly, to view raw or .psd files, you then have to buy a codec pack. All such plugins are free with IrfanView, so this was disappointing.
Curiously, though, since installing FastPictureViewer, IrfanView just flies along. It now loads a 47.5mb .NEF almost instantly, even when double clicking the image in an explorer window. The image is actually loaded by the time the window opens, and there is no discernible delay when scrolling backwards and forwards through a folder. I wondered if there was some sort of caching going on, so I fired off a few shots to make sure and tried again. Same result, the image loaded instantly.
I then took it a step further and tried it with a 152mb .jpg file. FastPictureView took just under 7 seconds to load the image, and IrfanView took just over 3 seconds. The big advantage FastPictureView has is that it extracts the .jpg element of large .tif files, which IrfanView doesn't. I'm not a great user of .tif to be honest. If I need layers etc. I use .psd or, if not, I use .png.
Like I say, I don't know why IrfanView is now faster than it ever was for me, but it is. It could be that FastPictureView installs a codec of some sort which is then utilised by IrfanView, but I really have no evidence apart from my own eyes.
Even with Photo Mechanic 5, I no longer see that half second of pixelation whilst the full image window redraws a full size .NEF, so I know something has definitely changed.
Thanks for getting to the end of the least scientific photographic experiment ever undertaken