Yeah, I can confirm that you can just throw thousands and thousands of instances into a level with essentially negligible performance impact, and I do this with 64 separate actors each of which generates a huge number. My advice would be 36 instanced static mesh components, each at 10° intervals, spawning an instance of itself for each point in that chunk. A simple material parametrized to calculate the instance position relative to the center point world space vector parameter and build the color based on that would be inexpensive, and using a simple cube with an unlit shading model would be quite performant.