I was wondering why FS which usually uses only 8-10% CPU at for my 20 active calls was suddenly using 60%.
I was pointed to the leap-second being a possible cause.

So, as per: http://marc.info/?l=linux-kernel&m=134113577921904
I ran: $ date -s "`date`"

and the CPU usage went immediately back to the norm. Not sure if it glitched the audio when doing so, though...

This is just a PSA and YMMV.

-Avi