Easy fix, as in turning off and not using Apple Music (even though some wanted to use it, like yourself)? The same easy fix as, turning on reduce transparency to reduce lag?
8.4.1 was not perfect by any stretch. 9.2 b1 is running very well on my 6+ and is much more stable than any iteration of iOS 8.
If you base everything on fluidity, you'll always be disappointed. It's never going to be perfect, just like 8.4.1 was not.
8.4.1 wasn't perfect, 8.3 was. As far as animations go though, 8.4.1 was great except for buggy music app, but there's nothing we could do about that. However, that was just one thing, but iOS 9 lags on almost everything on my iPhone 6.