that trigger once in the loop doesn't do anything, so it is creating new minimap objects for each obj_Ore1 on every tick... which will very quickly create thousands and thousands of objects.
what you might want to do is give the obj_Ore1 an instance variable that holds the UID of the minimap object assoiciated with it (and do the same for any other objects that need to appear on the minimap), then create the minimap object whenever you create a new object and store the minimap version's UID so you can pick it and update it as needed.
another way would be to make the obj_Ore1 a container so that the minimap object gets automatically created and associated (picked) with its parent object.