Optimizing question

I am not sure if this is an asset or world creation question. I have a 2K texture for my rock cliffs. I need to add a couple hundred small rock instances. They would only need a 256 pixel texture to look good, but I could reuse the 2K rock cliff texture on them.
What is better for performance, reusing the big texture on a lot of small assets or applying a small version of the texture to them?