Well, I guess resolutions is the most important factor. You should probably use png or tga as the format. Jpeg’s will do too, but they are compressed (unless you use maximum quality), so you can see it in the image quality. I guess grayscale images load quicker since they’re smaller.
If you mean real-time viewing, it depends on your graphics card memory (VRam) not system Ram. With programs like Shake, you can specify an image proxy that basically uses a lower resolution image so it loads much faster although Shake uses Ram. That might be quite useful in Blender. It would generate a lower resolution texture on the fly and then use that for real-time drawing scaled up but use the original for rendering.
When I said damn the extra ram not effecting my pc I meant that it is more glitchy when surfing the web or using an image editing program than it was before, without being any quicker. Not that it wasnt aiding the running of my 3d stuff…
I shall have a look at this shake.
I thought jpg would be poor due to its image quality reducing effects, but this is for my furthest LOD so detail isnt very important at all really, you wont see much of it no matter how good quality the texture is.