Actually, to drastically reduce CPU/GPU-consumption, it’s enough if the editor isn’t in the foreground. I am restoring it everytime by hand now (having to alt tab, then restore, then move, then klick into the window again). There is no performance difference.
It’s just very annoying to do this every time just to view the active blueprint window and are being able to use the debugger. This wouldn’t be the case, if the window would just open on top instead of minimizing the editor.