Xfinity Stream Portal taking a lot of cpu power

It's due to the UI and need to lower the graphics or whatever is going on with that overlay! 
When the video is Paused and the UI hides and I press play then the video plays perfectly and in 4k at 60fps but the moment the mouse hovers on the browser and that nasty UI shows up then my PC starts to scream and cpu spikes and the fans  goes crazy! It's happens on every browser I installed From Firefox, Chrome, Edge even Brave, Please can you guys fix that!?