Ok, I discovered that these GC messages were caused by a repaint() in a timer in my code. If I comment the repaint() out I don’t get these messages in a loop, so this was misguiding.
But I still have strange issues: each repaint() calls in my app generates GC_FOR_ALLOC and GC_CONCURRENT messages, but also mouse events:
Each time I press a component in my app, when mouseDown gets called, these messages appears (and the app slows down). What is really strange is that I still get these messages even if the mouseDown implementation is empty! I really don’t get it, but I’ll try to make a minimal app to locate the problem more precisely.