Paramount+ very sluggish when using the Xfinity box

Streaming Paramount+ through the Xfinity box is almost unusable -- very, very, very sloooooow. Takes forever to load content; constant circle/loading/freezing while streaming. I've tried the recommended power off/on, restarts of the cable box, modem and TV and uninstall/reinstall of app ... to no avail.

I have no issues whatsoever when streaming to my Mac mini, which is ethernet-connected. So I am almost sure that the issue is the streaming from the Xfinity box through the HMDI cable to my TV. (Tried a different HDMI cable too.) I suppose that I could verify this by removing the ethernet cable from the Xfinity box and connecting it to my TV (and removing the HDMI cable from the TV), but what's the point? If I do that I might as well get rid of the box, right?

I have the Choice TV package (primarily for the local broadcast channels) and Connect More (200 Mb internet speed). Also, of the other streaming apps that I subscribe to (Apple TV+, Hulu, Max, Netflix, Peacock, Prime), only Peacock exhibits some of the slowness that I see with Paramount+ (but where Paramount+ is a 9.5 on the slowness scale, Peacock is about a 2, so liveable). All of the other apps stream the actual content just fine after the initialization of the app, which is typically very slow (likewise, exiting the stream or app is also very slow).

Any suggestions? TIA