Having the same issue and I'm also on AT&T. I tried connecting to Krystal.co.uk and got the same extremly slow loading. If I try connecting through a proxy or vpn, the sites work fast and fine. For me the problem always happens after 8pm CDT and usally lasts untill 4am or so the next morning. Clearing temp files/resetting router/alternate browser/flushing dns/changing dns, equals no improvement, so it definately seems to solely be at&t's fault. One suspicion of mine of the cause is the heavy east coast flooding. AT&T might be doing repairs during night hours in those areas.