A couple of weeks ago there was an announcement about some significant performance improvement (something like 10% across the board if i remember correctly, I'll try to dig up a link tomorrow) would land in the nightlies in the next few days. I haven't found it in the changelogs, but i guess it should be in there by now.
Subjectively recent nighties do seem more snappy and I'm pretty happy battery life seems to be improving slowly too.
I don't see the KSM setting in my advanced settings anywhere though... Guessing it has been enabled by default now maybe...