If your cable speeds drop during peak periods - late afternoons/evenings and weekends - but speeds are better at other times like 3AM, your node is almost certainly overloaded. This can be a major battle with the cable co, and it seems to happen more often with smaller cable providers as opposed to giants like Comcast. I fought it with Cox for two years. Conveniently they don't schedule techs to come out evenings or weekends so they never could reproduce it. The cards are stacked against you, so it's up to you whether to deal with the slow speeds or try to fight support for better speeds, or switch to DSL.