Quote - What I mean is, if I load a figure, and hit render, first it obviously has to load all the textures into memory - or I guess its storing them in a folder on the disk temporarily.
Why does it do that by the way? What's wrong with using RAM, or just accessing the textures from the runtime location instead of making copies?

It does this for at least a couple of reasons, the main on being that the new files written to disk include several mipmapped LODs, and caching them in this format means that they can be paged in as required to avoid memory problems.
This is an important improvement and negates any texture size / quantity issues during rendering (preview is another matter though).