Hello. I'm using OctaneRender plugin for Blender v29.14 with my GeForce RTX 4090.
At our sun source, 100k spp (samples per pixel) at Path Tracing (PT) kernel - 540p vs 4320p:
4320p is much better caustics than 540p. But 4320p is ~39x longer render time than 540p but 4320p is 64x higher resolution screen than 540p. Therefore, 4320p has 1.6x more performance efficiency.
Best regards.