Every 5 seconds a Short Spinner

I discovered on my Media Library every 5 seconds a Short Spinner.
My question: Might this be the reason during initialization of the database. I have started the function for two days. But as I remember the Progress of the initialization was different in the past. Now I don‘t know the progress when the database init has finished. It‘ s now more than 4 Hours in action.
Otherwise I have no Problems with my Music DB but it‘s Strange to see every 5 seconds a Spinner at the RS520 display and at the both Apps Rose One and Rose EA (IOS). Any ideas what is happening. DB: 6300 titles