With Fire TV stick Amazon unacceptable

The library of BR improved in the user interface constantly - also use this app for the Amazon Fire TV stick.
The app I have installed on the Fire-TV-Stick.
Unfortunately jerky transmission - obviously buffer problems or other problems.
I have the Fire TV stick with Smart TV and with Raspberry PI 2 B on the same TV compared (BR) - also with an Android system
(Tablet PC) - in the same home network. The APP BR Video library is not to be used on the Fire-TV-Stick, as about every 30 seconds, sometimes even less the stream is and recharging starts.
My criticism is not directed against the user guidance. As long as the stream does not run I will spare me further comments.
Amazon is doing a disservice to it, - if such shortcomings occur. The advertisement promises more here.
Product matures at the customer. The Amazon has this necessary is incomprehensible for me.
Interestingly, the YouTube app runs on the Fire-TV without any problems - apparently better implemented or optimized.