1) Clear all your history
2) clear any cached items such as cookies or saved passwords
3) Make sure You are using a decent up-to-date browser (I would recommend Chrome)
4) Check with your ISP to ensure your service correct and you have not exceeded your periods downloads.
5) Check a variety of sites to ensure it is not simply a promblem related to the site.
6) Hope for the best
7) ensure no background softwares (such as torrent softwares) are downolading data.
8) If you are still having big problems, you probabblly need to getr your computer servied or something.