Where possible, i. e. when not keeping references across functions, use the
_load_() methods instead of the _get_() ones from gobject-introspection, which
is faster and less prone to memory leaks:

  g_callable_info_get_arg () → g_callable_info_load_arg ()
  g_callable_info_get_return_type() → g_callable_info_load_return_type ()
  g_arg_info_get_type() → g_arg_info_load_type ()

https://bugzilla.gnome.org/show_bug.cgi?id=615982