I think sundays are slow all over the internet at large.
I have been going to internet message boards/chat rooms for over 12 years and this has been true. Nothing happens on Sundays and it is very nice. I read somewhere that 'Primetime' for the internet is between 8:00 AM & 5:00 PM during the weekdays. That is when most of the traffic occurs on all websites and there is only a small spike at night, but not too much. Of course, that small spike happens for porn sites. So, apparently, everybody checks their 'normal' websites during the day and then looks for porn at night. That makes sense.
Also, summer is really dead. All the college kids are home and don't have the luxury of the fast connection back at school, so they are usually doing other things.
Honestly, I really like the slow and relaxed atmosphere on Sundays. I am usually drowning in posts, so I catch up on so many that day. Sundays have always been slow for me. It is a perfect day to catch up on cleaning, laundry, gaming and posting. Recharge your batteries and let the forums have a rest.