Amazon Music appears to be continuously consuming over 25% of CPU utilization, even while music is not being played.
I contacted tech support about this issue using the Amazon support services Chat feature. I was told that the app was probably "updating the library" (or something along those lines), and that after a while I would see the CPU utilization drop to something very low. Even after 48 hours, the CPU utilization was still over 25%.
After some playing around with various software development tools, it appears to me that this has something to do with some of the "adds" or banners that appear on the user interface of the app. I'm still doing some diagnostics, so I have no hard facts yet.