Unfortunately there can be a lag. The timing of the metronome is bad on some devices (mostly Nexus). This is because we use the Android 'SoundPool', an Android provided component for sound generation. It is quite unreliable and flawed on various on this very devices. Please see: https://androidbycode.wordpress.com/2015/02/04/nexus-lollipop-soundpool-load-not-so-sweet This has a negative effect on functions such as the metronome. We have planned to switch to a new solution to generate the sounds.