TWC is famous for overloading their nodes. I'll bet your speed loss is in peak times 7pm to 12 midnight. Caused by overloaded nodes with people streaming netflix's and other stuff like that. Like Pgoodwin1 said keep chipping at them and keep asking for you $20 discount like I did. They got tired of giving me discounts and finally moved me to another node, now all is good until they overload this one. Then back to the discounts until they move me again or put in a new node. Just my 2 cents.