Quick shift preview for previous computed/cached renders
The aim of this option is to eliminate the need to re-render the whole material when you just want to compare two settings and going back and forth.
It would work like a clipboard for the material previewer
Everytime you "record/save" a computed material you could put all the textures that goes with it into a first entry.
Then you would capture/save a second set of baked textures that have been changed after some tweakings.
And then, quickly visualise the two materials in the texture & 3D view by just alternating the two sets of textures instead of waiting for everything to be rendered over and over again. That could be also great to have even more clipboard slots like a 3rd and a 4th entry.
That could be a huge time saver and avoid a lot of headaches issued by the computing time of big graphs.