Does your website traffic decrease during Christmas, or any holiday? Mine does. My traffic is mostly US based and my traffic has gone way down. I saw the same thing last year so I know it is holiday based and will return after the holiday is over. In fact, I see this during most holidays.
I read the other day that 94.5 million americans will be traveling during the Christmas seasons. This means they can't get online as much as they did prior or after. :|