Option to not render breadcrumbs.

includes/admin.form.inc

@@ -74,6 +74,12 @@ function islandora_repository_admin(array $form, array &$form_state) {
           '#description' => t('Displays an extra print tab, allowing an object to be printed'),
           '#default_value' => variable_get('islandora_show_print_option', FALSE),
         ),
+        'islandora_render_drupal_breadcrumbs' => array(
+          '#type' => 'checkbox',
+          '#title' => t('Render Drupal breadcrumbs'),
+          '#description' => t('Larger sites may experience a notable performance improvement when disabled due to how breadcrumbs are constructed.'),
+          '#default_value' => variable_get('islandora_render_drupal_breadcrumbs', TRUE),
+        ),
       ),
       'islandora_namespace' => array(
         '#type' => 'fieldset',

includes/breadcrumb.inc

@@ -25,10 +25,13 @@
  *   drupal_set_breadcrumb().
  */
 function islandora_get_breadcrumbs($object) {
+  $breadcrumbs = array();
+  if (variable_get('islandora_render_drupal_breadcrumbs', TRUE)) {
     $breadcrumbs = islandora_get_breadcrumbs_recursive($object->id, $object->repository);
     array_pop($breadcrumbs);
     $context = 'islandora';
     drupal_alter('islandora_breadcrumbs', $breadcrumbs, $context, $object);
+  }
   return $breadcrumbs;
 }
 

islandora.install

@@ -47,6 +47,13 @@ function islandora_uninstall() {
   $variables = array(
     'islandora_ds_replace_exclude_enforced',
     'islandora_defer_derivatives_on_ingest',
+    'islandora_base_url',
+    'islandora_repository_pid',
+    'islandora_use_datastream_cache_headers',
+    'islandora_show_print_option',
+    'islandora_render_drupal_breadcrumbs',
+    'islandora_namespace_restriction_enforced',
+    'islandora_pids_allowed',
   );
   array_walk($variables, 'variable_del');
 }