I agree with Robert. It's not DNS. Probably just the amount of
traffic. That can be caused in a number of ways.
If you're ever interested in how the Internet as a whole is doing, go
here: http://www.internettrafficreport.com/main.htm It can be a good
indication if there are issues. Remember that if a major router is
down, traffic usually gets shuffled off somewhere else & that can lead
to delays. Sometimes it's as simple as your signal hitting a critical
number of hops; more than 15 and you generally start to notice it
(actually, it's an accumulation of time between hops & a couple of slow
hops can make 6 or 8 too many). Other times, it's just that too much
traffic gets re-routed to other major points. That sort of thing has
been getting to be less of a problem over the years as the hardware
gets 'smarter', but can still be a pain if the point is big enough.
A couple of years back, someone dug up one of the major fiber feeds
near Chicago. We had issues with our sites in California (we're east
coast US) for several days solid & then intermittently for weeks.
Aquisitions are a major source of delays, too. When Algx bought IDS
(?), they changed all the routing schemes on the old network. We had
issues for several days before things settled down & the tables all
sync'd up. Usually, you don't get a delay due to this, just 404's, but
delays can be part of it.
Major events can also clog the connections - so blaming it on the Pope
might not be too outrageous. Residential Comcast customers usually
notice a 3pm slow down. That's when all the kids get home from school
& suddenly hit the network.