I have other TVs with FireSticks. They don't have the problem. All use WiFi (not in the 5 GHz band). After that realization I was able to fix the problem.
The only TV that was wired used the Amazon FireStick network interface module. I removed the Amazon wired interface module and instead used WiFi on the poorly performing FireStick. The 2.6 MHz band WiFi speed tested 80 Mbps and the 5 MHz band was 90 Mbps. Previously, the wired network speed had tested at 100 Mbps. The FireStick then behaved well when fast forwarding commercials, etc.
So something is going on in the Amazon wired interface module. Perhaps it is buffering? I had purchased the wired interface module to presumably speed up my network connection to the FireStick. That was a waste of money.
Thanks for your patience and assistance.