It only seems to be certain ip addresses. I was on the phone with Comcast support talking to one of their upper level techs and he was telling me they are performing "upgrades" to their network for the next 30 days or so. Durring this time they are routing traffic from bad network to bad network while they upgrade putting extra load on old equipment while they do it.
I get great pings and download speeds as long as the ip address I connect to isn't routed through the over-worked router.
Sad thing is I get over 1k ms pings from the Temecula area to Irvine where the WoW servers are, less than 60mi away.
Anyhow, look for this type of poor service for the next 30 days while they "upgrade".