I haven't seen any behavior to indicate a virus or malware and have also scanned for such. This ONLY happens when I stream Xfinity. I don't have any difficulty with any other streaming service. Netflix, Amazon, YouTube, etc all play beautifully. In addition, my computer is only a couple of months old, and not overloaded with lots of programs. Also, I would think if this was due to a "weak signal" or such, that it would be a problem with more than just xfinity streaming.
As soon as an xfinity streaming video begins, my cpu jumps to almost 100%. Nothing else comes close to using that much cpu on my computer.
As there are dozens and dozens of posts just like mine, it would seem that the issue is clearly on the Xfinity end. It is incredibly frustrating to pay for a service that is useless.