If you really want to test the power-of-two memory management, run a monitor utility while rendering a test scene with maps of, say, 512, 600, 900, and 1024 consecutively. As for reduction; I have a couple of texture sets I love but they are huge. So I've also got clearly-labeled 50% reduction in pixel size (resaved as JPEG at 100% -- practically no compression) and even a new MAT pose or two to go with them.