I have an iPhone 6 Plus and am running Spotify version 126.96.36.1995. The app freezes all the time during playback. For example, I will start playing a song. The song will continue to play but the UI freezes and is unresponsive. I can try to press the "next track" button but nothing happens. Then, anywhere from 45 seconds to 2-3 minutes later, the app recognizes my button press and advances to the next track. This is beyond frustrating and it seems like paying for premium is a waste.