Replying before they prematurely lock this thread like they have on others, with no solutions provided. Inquire about getting your node split. Techs and other Cox reps have told me that node utilization above 70% or above 80% will cause packet loss for everyone connected to the node. Trust me that Cox will drag their feet on this- many people have the same complaint as you, since Cox's infrastructure is simply not robust enough to handle consumer demand.
You could consider filing an FCC complaint if Cox is refusing to provide you any solutions. Doing so jumpstarts a separate internal process for a Cox rep to review your case. Good luck.
Who do we make the node split inquiry to? 10 times out of 10 I'm getting a tech who doesn't have any idea what the problem is since my 'speeds look good'. At this point, they've stopped answering emails, which is fine because they contain no information.