Hi,
I recently made a heavy scene (with 168 x 15K images). In order to work in good conditions and optimise the project, I made a few scripts. This is one of them. It swaps between low to high resolution textures for rendering.
1 - Create a low resolution version of your images, add “low_” to the name of the file (image.jpg --> low_image.jpg) and put it in the same folder(s) of the original.
2 - Use the low res for texturing
3 - Activate the add-on.
Hope it helps