This explains a lot actually. If the big ISPs such as Verizon and Comcast/Time Warner are throttling speeds or imposing caps on data transfers after so much bandwidth has been used, it's no wonder people have been seeing as much lag as they have in game. Level3 is just a CDN (content delivery network) and only function to interconnect the major ISP networks with each other. Once traffic which seems like it's functioning normally leaves your ISP and hits Level3, the big ISPs are shrinking their "pipe" on how much data can flow, which essentially slows down EVERYTHING.

TLDR: Blame Netflix for having all its subscribers streaming content since their network traffic accounts for over half of the data transferred over the internet now. :P