Without using SuperContainer, are there some best practices listed somewhere that ensure the best performance when loading up a solution with images etc.

In my case I was considering capturing a scanned version of a doc to keep as a reference against the key'd in version. One thought was to create a separate file and externally reference them. Also to make sure they are scanned in at screen resolution and in black & white. Am I on track?

that would suffice. If you have "opener" files on the users desktop you could store the images locally to each computer. Thus all references can come from this source vs. pulling data from the server.

You'd have to craft some way to update the opener files should you decide to rollout changes to images.

Another option if the images are for 'background' style images or other visual elements some have used a web viewer to display and then just store the images on your web server.