So I find that my MySQL database is running high on CPU all of a sudden. I optimize the tables etc and no difference. I hunt around the internet to find that there seems to be a problem with this years leap second adjustment which sends MySQL into orbit.

The solution reset the date

date -s "`date`"

and it dropped back to normal.

Credit goes to this lady here http://www.sheeri.com/content/mysql-and-leap-second-high-cpu-and-fix