I haven’t gone back to CM10.1 ROM for awhile now on my Nexus S but I tried the latest CM10.1 nightlies and WOW, what a difference it made in performance.
I am used to running other AOSP ROMs with lots of customization but the latest CM10.1 nightlies are pretty darn good as far as multi-tasking between large applications like graphic-intensive games. Also you will get the latest Android 4.2.2 with stability you can depend on.
Best of all, Nexus S and Nexus S 4G are still being supported “officially” by the CyanogenMod team.
CM10.1 ROMs don̵