Editing post don't save existing meta fields

Hi,

i have a problem - don't know if it's a general problem or a problem only with this plugin with GROUP (COLUMNs) extension.

I have this metabox:

$meta_boxes[] = array(
	'id' => 'mygallery',
	'title' => __('Gallery',TEXTDOMAIN),
	'pages' => array( '_products', '_other', '_other2' ),
	'context' => 'normal',
	'priority' => 'high',
	'public' => true,
	'show_in_nav_menus' => false,

	'fields' => array(
		array(
			'id'    => "{$prefix}gallery_strip",
			'type' => 'group',
			'clone' => true,
			'sort_clone' => true,
			'fields' => array(
				array(
					'name' => __('Thumbnail',TEXTDOMAIN),
					'id'   => "{$prefix}photo_thumb",
					'type' => 'image_advanced',
					'max_file_uploads' => 1,
					'max_status' => false,
					'columns' => 3
				),
				array(
					'name' => __('Detail',TEXTDOMAIN),
					'id'   => "{$prefix}photo_detail",
					'type' => 'image_advanced',
					'max_file_uploads' => 1,
					'max_status' => false,
					'columns' => 9
				)
			)
		)
	)

);

On my edit page a have more metaboxes - everything works fine.

I noticed, that when i try to edit a single page, it takes a while, when all information in metaboxes are loaded and visible on the admin site - specially this metabox with photos (it takes for example 5-6 seconds to load).

If i'm doing only a small edit and save the post before all metaboxes are completaly loaded, then these unloaded data are missing (empty).

What can I do?