red6
, which firestick do you have? I had to upgrade to the 4K one as the one before that which only did 1080p didn't have enough processing power/ram to run ESPN all correctly. It would buffer or shudder and not be smooth. Most other apps were fine. But problem went away with no other changes when I changed to the 4k model.
Kids have the same issues with those cheap fire tables. They are all under-powered and Amazon puts so much of their addware on them that they never run well.