I have a feeling there's some work going on in town that may be affecting overall connection speeds but this shouldn't prevent specific sites from loading. Try loading (and then using)
http://www.speedtest.net and see if the results match what you're paying for!
My latest test:-
http://www.speedtest.net/result/1719237893.png
I'm supposed to get a download speed close to 20 Mb/s so I'm running on only half speed at this point, yet my upload speed is consistent with a normal reading of around 2.0 Mb/s.
Usually a site is slow because it is receiving heavy traffic and this may be due to normal usage for a particular time of day or it may be hackers applying a DoS (Denial of Service) attack or the like.