So, when is the smooth scrolling Mavericks' API going to be implemented? iTunes is so janky, specially when compared to the silk which is Safari when scrolling.
I haven't noticed major scrolling problems, but the search functionality is so bad it locks up the UI while sputtering to return results. And forget trying to type anything while it's searching. There's several things I think iTunes 11 improved, but searching is far far worse now. And when people have libraries that number in the tens of thousands, searching is one of those things that should have spit and polish.
But that's the general problem with iTunes. It's not a focused product. There are so many competing internal interests for engineering time -- iTunes Match, iTunes Radio, iBooks, iTunes Store, and oh yeah music -- that it doesn't feel anymore like an Apple product. Almost feels like a Microsoft product. As Jobs said, being focused is about saying "no" not "yes", but they seem to say "yes" to shoehorning into iTunes whatever product they want us to buy this week. I mean, does it even make sense that you can buy books and films inside a music app? They need to just make a separate Media Store app, and leave our music alone.