Very slow X1 box response

Since installation, using Xfinity via the X1 box is excruciatingly slow. Loading Disney+, Netflix, or Paramount+ takes 60+ seconds just to get to the "home" screen. Then, trying to select anything forces you to wait a few seconds for a button click on the remote before it actually happens on the screen. Even just pulling up the Guide and browsing through it is slow. Button response during live or recorded shows is also very slow. (2) wireless boxes and (1) other hard wired box work acceptably well... just the main X1 box has this problem. It has been replaced twice with no change. (2) techs have come out and both said that my signal is "tanked" (to use their language). They say that the recently installed cable running down our road should have had "boosters", or "amplifiers" installed, but that they do not. They said that the cable installation is under review for re-engineering, and they have no time frame for when this will happen.

Has anyone else experienced this type of problem?

In addition, 1200 Gbps speed is actually consistently 300 to 340 Mbps. This in itself is acceptable to me since I was getting 10 Mbps from my previous wifi supplier.  But this, too, may be a result of data "garbage" in the main cable line.