It is mostly U.S. time zones. When America wakes up it gets a lot more slow.
Just prior to 8:00 central time and Lunch Central time seems to me to be the worst.
In the middle of the night central time it is pretty quick.
I am not sure if it is bandwidth or just too many hits on the database. I know sometimes it just loads with an internal server error so I suspect too many hits on the database at once.