Buffering is the enemy of cord-cutters everywhere. Your Amazon Firestick 4K is powerful, but it comes heavily bloated out of the box. Here is exactly how to fix IPTV buffering.
Clear the Cache
Go to Settings > Applications > Manage Installed Applications. Find your IPTV player, click on it, and select ‘Clear Cache’. Do NOT click ‘Clear Data’ or you will delete your login!
Turn off Data Monitoring
Amazon loves to ping servers to check what you are watching. Navigate to Preferences > Privacy Settings, and turn off Device Usage Data and Collect App Usage Data. This frees up crucial RAM.