Nexus S - Cyanogenmod for Android 4.3 or 4.2?

I know it's nuts, and yes I'm retiring this dinosaur soon and getting a Nexus 5, but for now I'm curious which one would perform better on this 512MB single core device. Which one is less RAM and processor intensive?

I know kitkat is the one to shave things back to being 512MB-acceptable, but I'm guessing no ROMs for that will be available anytime soon?