Well put the modem in bridge mode and try it direct or with your own router.
Either of those pages listed have a ton of scripts and cross-site page referrals. I got multiple warnings of stalled, slow loading scripts on Facebook over the weekend, which is unusual. Lots of things will affect web loading speed outside of your modem and computer hardware. -- If it's important, back it up... twice. Even 99.999% availability isn't enough sometimes.