I think when I looked at it.... 20 meg service dropped down to 12 or something after the burst.... I assume this is the minimum that they have to provide. So, Fios at 20 K was much better then Xffinity at 12 K at steady state.

So basically xfinity has software that throttles your connection speed as a function of time and then squeezes your speed as they fit as many people on the loop as they can sell.
So... you have to be a squeaky wheel when your 20 /5 which is really 12/5 drops below that.... Same ol Sxxt from Comcast.