Interestingly enough the same happens on both Spotify's desktop and Chromecast / Apple TV application when you "song surf".
If you rapidly keep skipping through a song, then to the next one and repeat, the performance will keep on tanking. After a while it'll take 5-10 seconds just to load a song, going to other UI sections will take 3-5 seconds to load, and eventually the application completely locks up and soft reboots itself.
Javascript garbage collector wouldn't take so long... probably it's launching a new thread or process (for example, DRM decryption) for every song, and there becomes too many of them. Or it runs out of memory and starts swapping.
If you rapidly keep skipping through a song, then to the next one and repeat, the performance will keep on tanking. After a while it'll take 5-10 seconds just to load a song, going to other UI sections will take 3-5 seconds to load, and eventually the application completely locks up and soft reboots itself.
Probably JavaScript garbage collectors getting overwhelmed.