I have worked with my company's IT department to trace the slowdown and it's most definitely ALWAYS at alter.net. Interestingly I read about Verizon purposely allowing the ports at Alter.net junctions to become saturated with traffic. Rather than open more ports to balance the traffic they just turn a blind eye -- why? Because they own a 50% stake in Redbox and the want customers to choose their VOD services rather than Netflix, iTunes and Amazon Prime. So the best way to do that is to make those kinds of services so slow it's unusable. Cogent and Akamai (which provide CDN services for iTunes and Netflix) are well aware of Verion's shady practices and have repeatedly (and publicly) requested a solution from Verizon but nothing has been done. Partially you can blame the FCC for deregulating broadband to begin with - a move which they now openly regret. Remember when Google had the big push behind net neutrality? Well they suddenly got quiet about it -- why? Verizon offered them a deal to ensure their traffic goes through is the speculation. I have the 300Mb plan and if I connect to my akamai hosted FTP at say 9am I get close to 30MB per sec. 11:30am/noon-ish until about midnight I get 600KBps to 900KBps. There is absolutely NO WAY the internet as a whole would slow me down that drastically, especially to Akamai who has built its entire business on providing faster and more reliable transfer rates during congested times.
What will it take for Verizon to listen to their paying customers needs instead of playing this childish 'you can't play in my treehouse' games with other networks.
I hope Google FIber comes here soon because if this isn't resolved I'm jumping ship in an instant. This affects my business.