Internet has been so slow for past couple of weeks?

Okay, so my internet has been acting very strange recently. I use both mozilla firefox and google chrome, and for the past couple of weeks, i've been noticing enormous differences when i hop on the internet. It takes at least 15 seconds just to load a website on either mf or gc, and it takes forever to load videos (youtube, e.t.c). I'm running McAfee and Norton currently (have been for years), and it says there are no problems involved. Does anyone know how to fix this problem? I've tried deleting things off the harddrive as well as the history but it doesn't work. I'm tired of waiting so long for something that shouldn't have to be!