Simple example on how to avoid static taxonomies by caching their IDs in a cache.

patch-settings-filter.diff

diff --git a/lib/filter/QubitSettingsFilter.class.php b/lib/filter/QubitSettingsFilter.class.php
index 8894026..6e091fc 100644
--- a/lib/filter/QubitSettingsFilter.class.php
+++ b/lib/filter/QubitSettingsFilter.class.php
@@ -27,7 +27,34 @@ class QubitSettingsFilter extends sfFilter
     // Overwrite/populate settings into sfConfig object
     sfConfig::add(QubitSetting::getSettingsArray());

+    // Load custom taxonomies
+    $this->loadCustomTaxonomies();
+
     // Execute next filter
     $filterChain->execute();
   }
+
+  protected function loadCustomTaxonomies()
+  {
+    $cache = new sfAPCCache;
+
+    if (null === $taxonomyId = $cache->get('id_taxonomy_repository_types'))
+    {
+      $criteria = new Criteria;
+      $criteria->addJoin(QubitTaxonomy::ID, QubitTaxonomyI18n::ID);
+      // $criteria->add(QubitTaxonomy::USAGE, 'Custom taxonomy (usask.ca)');
+      $criteria->add(QubitTaxonomyI18n::CULTURE, 'en');
+      $criteria->add(QubitTaxonomyI18n::NAME, 'Repository Types');
+      if (null !== $taxonomy = QubitTaxonomy::getOne($criteria))
+      {
+        $taxonomyId = $taxonomy->id;
+
+        $cache->set('id_taxonomy_repository_types', $taxonomyId);
+      }
+    }
+
+    // Store the ID in the app configuration
+    sfConfig::set('id_taxonomy_repository_types', $taxonomyId);
+  }
 }