Repost question from 2013. I have same problem.

["Konstantin P." <ria freelander gmail com>]

The following code spawns a window --

if (connect_build_object != NULL) {
    g_object_unref (G_OBJECT ( connect_build_object ));
    object = NULL;
}
    connect_build_object = gtk_builder_new();

gtk_builder_add_from_resource ( connect_build_object, "/erg/app/ui/main_window.ui", NULL );

    gtk_builder_connect_signals ( connect_build_object, NULL );

connect_window = GTK_WIDGET ( gtk_builder_get_object ( connect_build_object, "connec" ) );

    gtk_widget_show ( connect_window );

Where connect_build_object is a global variable.

Before spawning, it's checked if connect_build_object is initilized, if that's the case, its destroyed by g_object_unref.

Closing the window calls the default handler.

Problem: Each time I open and close a window, memory usage increases.
And it does not decreases after builder unref.
 Why it is increases, and how I can avoid this?