This is most common on Peacock but now it happens on Paramount+, Hulu, and Netflix.
Video freezes then stutters along a frame or two at a time with intermittent freezes. Sound will start and stop but went going it is at full speed.
Remote stops working entirely. When it does work it is on a delay. Eventually after a couple of minutes the remote works or the device reopens on the app icons screen.
The Roku (Express) sometimes has a solid white dot sometimes its dark, and sometimes the light goes on and off when you are trying to get the Roku to work by using the remote.
I have 12 or 18 Mps internet and nothing else is slow or glitchy even computer games. I am only watching streaming with maybe web browsing on my PC.
If you're using your TV's USB port and not the supplied power adapter give the power adapter a shot. Try a different HDMI cable if you have one and/or a different HDMI input on your TV.