diff --git a/lib/Alchemy/Phrasea/Collection/CollectionRepository.php b/lib/Alchemy/Phrasea/Collection/CollectionRepository.php
index aadf24148c..865ece521d 100644
--- a/lib/Alchemy/Phrasea/Collection/CollectionRepository.php
+++ b/lib/Alchemy/Phrasea/Collection/CollectionRepository.php
@@ -2,7 +2,7 @@
 
 namespace Alchemy\Phrasea\Collection;
 
-interface CollectionRepository 
+interface CollectionRepository
 {
 
     /**
@@ -21,4 +21,10 @@ interface CollectionRepository
      * @return void
      */
     public function save(Collection $collection);
+
+    /**
+     * @param Collection $collection
+     * @return void
+     */
+    public function delete(Collection $collection);
 }
diff --git a/lib/Alchemy/Phrasea/Collection/CollectionRepositoryRegistry.php b/lib/Alchemy/Phrasea/Collection/CollectionRepositoryRegistry.php
index 8aea2df32a..6acc5f0ee2 100644
--- a/lib/Alchemy/Phrasea/Collection/CollectionRepositoryRegistry.php
+++ b/lib/Alchemy/Phrasea/Collection/CollectionRepositoryRegistry.php
@@ -2,6 +2,7 @@
 
 namespace Alchemy\Phrasea\Collection;
 
+use Alchemy\Phrasea\Application;
 use Alchemy\Phrasea\Collection\Reference\CollectionReferenceRepository;
 
 class CollectionRepositoryRegistry
@@ -9,6 +10,11 @@ class CollectionRepositoryRegistry
 
     private $baseIdMap = null;
 
+    /**
+     * @var Application
+     */
+    private $application;
+
     /**
      * @var CollectionRepository[]
      */
@@ -25,13 +31,16 @@ class CollectionRepositoryRegistry
     private $repositoryFactory;
 
     /**
+     * @param Application $app
      * @param CollectionRepositoryFactory $collectionRepositoryFactory
      * @param CollectionReferenceRepository $referenceRepository
      */
     public function __construct(
+        Application $app,
         CollectionRepositoryFactory $collectionRepositoryFactory,
         CollectionReferenceRepository $referenceRepository
     ) {
+        $this->application = $app;
         $this->repositoryFactory = $collectionRepositoryFactory;
         $this->referenceRepository = $referenceRepository;
     }
@@ -70,6 +79,11 @@ class CollectionRepositoryRegistry
     public function purgeRegistry()
     {
         $this->baseIdMap = null;
+
+        $appBox = $this->application->getApplicationBox();
+
+        \phrasea::reset_baseDatas($appBox);
+        \phrasea::reset_sbasDatas($appBox);
     }
 
     private function loadBaseIdMap()
diff --git a/lib/Alchemy/Phrasea/Collection/CollectionService.php b/lib/Alchemy/Phrasea/Collection/CollectionService.php
index 3707aa0157..6e75c87780 100644
--- a/lib/Alchemy/Phrasea/Collection/CollectionService.php
+++ b/lib/Alchemy/Phrasea/Collection/CollectionService.php
@@ -162,8 +162,6 @@ class CollectionService
         $stmt->execute([':base_id' => $reference->getBaseId()]);
         $stmt->closeCursor();
 
-        $this->app['manipulator.registration']->deleteRegistrationsOnCollection($this);
-
         return;
     }
 
diff --git a/lib/Alchemy/Phrasea/Collection/Reference/ArrayCacheCollectionReferenceRepository.php b/lib/Alchemy/Phrasea/Collection/Reference/ArrayCacheCollectionReferenceRepository.php
new file mode 100644
index 0000000000..373eeab202
--- /dev/null
+++ b/lib/Alchemy/Phrasea/Collection/Reference/ArrayCacheCollectionReferenceRepository.php
@@ -0,0 +1,110 @@
+<?php
+
+namespace Alchemy\Phrasea\Collection\Reference;
+
+class ArrayCacheCollectionReferenceRepository implements CollectionReferenceRepository
+{
+    /**
+     * @var CollectionReferenceRepository
+     */
+    private $repository;
+
+    /**
+     * @var null|array
+     */
+    private $referenceCache = null;
+
+    public function __construct(CollectionReferenceRepository $referenceRepository)
+    {
+        $this->repository = $referenceRepository;
+    }
+
+    /**
+     * @return CollectionReference[]
+     */
+    public function findAll()
+    {
+        if ($this->referenceCache === null) {
+            $this->referenceCache = $this->repository->findAll();
+        }
+
+        return $this->referenceCache;
+    }
+
+    /**
+     * @param int $databoxId
+     * @return CollectionReference[]
+     */
+    public function findAllByDatabox($databoxId)
+    {
+        $references = $this->findAll();
+        $found = array();
+
+        foreach ($references as $reference) {
+            if ($reference->getDataboxId() == $databoxId) {
+                $found[$reference->getBaseId()] = $reference;
+            }
+        }
+
+        return $found;
+    }
+
+    /**
+     * @param int $baseId
+     * @return CollectionReference|null
+     */
+    public function find($baseId)
+    {
+        $references = $this->findAll();
+
+        if (isset($references[$baseId])) {
+            return $references[$baseId];
+        }
+
+        return null;
+    }
+
+    /**
+     * @param int $databoxId
+     * @param int $collectionId
+     * @return CollectionReference|null
+     */
+    public function findByCollectionId($databoxId, $collectionId)
+    {
+        $references = $this->findAll();
+
+        foreach ($references as $reference) {
+            if ($reference->getCollectionId() == $collectionId) {
+                return $reference;
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * @param CollectionReference $reference
+     * @return void
+     */
+    public function save(CollectionReference $reference)
+    {
+        $this->repository->save($reference);
+
+        if ($this->referenceCache !== null) {
+            $this->referenceCache[$reference->getBaseId()] = $reference;
+        }
+    }
+
+    /**
+     * @param CollectionReference $reference
+     * @return void
+     */
+    public function delete(CollectionReference $reference)
+    {
+        $this->repository->delete($reference);
+
+        if ($this->referenceCache !== null) {
+            unset($this->referenceCache[$reference->getBaseId()]);
+        }
+    }
+}
diff --git a/lib/Alchemy/Phrasea/Collection/Reference/CollectionReferenceRepository.php b/lib/Alchemy/Phrasea/Collection/Reference/CollectionReferenceRepository.php
index b90b02e1de..48dbfc94f5 100644
--- a/lib/Alchemy/Phrasea/Collection/Reference/CollectionReferenceRepository.php
+++ b/lib/Alchemy/Phrasea/Collection/Reference/CollectionReferenceRepository.php
@@ -33,4 +33,10 @@ interface CollectionReferenceRepository
      * @return void
      */
     public function save(CollectionReference $reference);
+
+    /**
+     * @param CollectionReference $reference
+     * @return void
+     */
+    public function delete(CollectionReference $reference);
 }
diff --git a/lib/Alchemy/Phrasea/Collection/Reference/DbalCollectionReferenceRepository.php b/lib/Alchemy/Phrasea/Collection/Reference/DbalCollectionReferenceRepository.php
index 63dd1eb06b..22ff361ed7 100644
--- a/lib/Alchemy/Phrasea/Collection/Reference/DbalCollectionReferenceRepository.php
+++ b/lib/Alchemy/Phrasea/Collection/Reference/DbalCollectionReferenceRepository.php
@@ -31,6 +31,8 @@ class DbalCollectionReferenceRepository implements CollectionReferenceRepository
     private static $updateQuery = 'UPDATE bas SET ord = :displayIndex, active = :isActive, aliases = :alias
                                    WHERE base_id = :baseId';
 
+    private static $deleteQuery = 'DELETE FROM bas WHERE base_id = :baseId';
+
     /**
      * @var Connection
      */
@@ -126,6 +128,19 @@ class DbalCollectionReferenceRepository implements CollectionReferenceRepository
         }
     }
 
+    /**
+     * @param CollectionReference $collectionReference
+     * @throws \Doctrine\DBAL\DBALException
+     */
+    public function delete(CollectionReference $collectionReference)
+    {
+        $parameters  = [
+            'baseId' => $collectionReference->getBaseId()
+        ];
+
+        $this->connection->executeQuery(self::$deleteQuery, $parameters);
+    }
+
     /**
      * @param array $row
      * @return CollectionReference
diff --git a/lib/Alchemy/Phrasea/Collection/Repository/ArrayCacheCollectionRepository.php b/lib/Alchemy/Phrasea/Collection/Repository/ArrayCacheCollectionRepository.php
index 45df2e1f6f..0373e02bf3 100644
--- a/lib/Alchemy/Phrasea/Collection/Repository/ArrayCacheCollectionRepository.php
+++ b/lib/Alchemy/Phrasea/Collection/Repository/ArrayCacheCollectionRepository.php
@@ -54,7 +54,16 @@ class ArrayCacheCollectionRepository implements CollectionRepository
         $this->collectionRepository->save($collection);
 
         if ($this->collectionCache !== null) {
-            $this->collectionCache = null;
+            $this->collectionCache[$collection->getCollectionId()] = $collection;
+        }
+    }
+
+    public function delete(Collection $collection)
+    {
+        $this->collectionRepository->delete($collection);
+
+        if (isset($this->collectionCache[$collection->getCollectionId()])) {
+            unset($this->collectionCache[$collection->getCollectionId()]);
         }
     }
 }
diff --git a/lib/Alchemy/Phrasea/Collection/Repository/CachedCollectionRepository.php b/lib/Alchemy/Phrasea/Collection/Repository/CachedCollectionRepository.php
index 5dd84f7c53..a7a414aee4 100644
--- a/lib/Alchemy/Phrasea/Collection/Repository/CachedCollectionRepository.php
+++ b/lib/Alchemy/Phrasea/Collection/Repository/CachedCollectionRepository.php
@@ -96,6 +96,15 @@ final class CachedCollectionRepository implements CollectionRepository
         $this->cache->delete($cacheKey);
     }
 
+    public function delete(Collection $collection)
+    {
+        $this->repository->delete($collection);
+
+        $cacheKey = hash('sha256', $this->cacheKey);
+
+        $this->cache->delete($cacheKey);
+    }
+
     private function putInCache($key, $value)
     {
         $this->cache->save($key, $value);
diff --git a/lib/Alchemy/Phrasea/Collection/Repository/DbalCollectionRepository.php b/lib/Alchemy/Phrasea/Collection/Repository/DbalCollectionRepository.php
index 0fe9827b06..860dcd1e5c 100644
--- a/lib/Alchemy/Phrasea/Collection/Repository/DbalCollectionRepository.php
+++ b/lib/Alchemy/Phrasea/Collection/Repository/DbalCollectionRepository.php
@@ -20,6 +20,8 @@ class DbalCollectionRepository implements CollectionRepository
                                 label_de = :labelDe, label_nl = :labelNl, prefs = :preferences, logo = :logo,
                                 majLogo = :logoTimestamp, pub_wm = :publicWatermark WHERE coll_id = :collectionId';
 
+    private static $deleteQuery = 'DELETE FROM coll WHERE coll_id = :collectionId';
+
     /**
      * @var int
      */
@@ -150,4 +152,13 @@ class DbalCollectionRepository implements CollectionRepository
             $collection->setCollectionId($this->connection->lastInsertId());
         }
     }
+
+    public function delete(Collection $collection)
+    {
+        $parameters = [
+            'collectionId' => $collection->getCollectionId()
+        ];
+
+        $this->connection->executeQuery(self::$deleteQuery, $parameters);
+    }
 }
diff --git a/lib/Alchemy/Phrasea/Core/Provider/RepositoriesServiceProvider.php b/lib/Alchemy/Phrasea/Core/Provider/RepositoriesServiceProvider.php
index 58bc0839a1..b8e3cffbd0 100644
--- a/lib/Alchemy/Phrasea/Core/Provider/RepositoriesServiceProvider.php
+++ b/lib/Alchemy/Phrasea/Core/Provider/RepositoriesServiceProvider.php
@@ -17,6 +17,7 @@ use Alchemy\Phrasea\Collection\CollectionRepositoryRegistry;
 use Alchemy\Phrasea\Collection\Factory\ArrayCachedCollectionRepositoryFactory;
 use Alchemy\Phrasea\Collection\Factory\CachedCollectionRepositoryFactory;
 use Alchemy\Phrasea\Collection\Factory\DbalCollectionRepositoryFactory;
+use Alchemy\Phrasea\Collection\Reference\ArrayCacheCollectionReferenceRepository;
 use Alchemy\Phrasea\Collection\Reference\DbalCollectionReferenceRepository;
 use Alchemy\Phrasea\Collection\Repository\ArrayCacheCollectionRepository;
 use Alchemy\Phrasea\Collection\Repository\CachedCollectionRepository;
@@ -150,7 +151,9 @@ class RepositoriesServiceProvider implements ServiceProviderInterface
         });
 
         $app['repo.collection-references'] = $app->share(function (PhraseaApplication $app) {
-            return new DbalCollectionReferenceRepository($app->getApplicationBox()->get_connection());
+            $repository = new DbalCollectionReferenceRepository($app->getApplicationBox()->get_connection());
+
+            return new ArrayCacheCollectionReferenceRepository($repository);
         });
 
         $app['repo.collections-registry'] = $app->share(function (PhraseaApplication $app) {
@@ -172,7 +175,7 @@ class RepositoriesServiceProvider implements ServiceProviderInterface
 
             $repositoryFactory = new ArrayCachedCollectionRepositoryFactory($repositoryFactory);
 
-            return new CollectionRepositoryRegistry($repositoryFactory, $app['repo.collection-references']);
+            return new CollectionRepositoryRegistry($app, $repositoryFactory, $app['repo.collection-references']);
         });
     }
 
diff --git a/lib/classes/collection.php b/lib/classes/collection.php
index 9982b15bc0..269f8e79d1 100644
--- a/lib/classes/collection.php
+++ b/lib/classes/collection.php
@@ -302,6 +302,14 @@ class collection implements ThumbnailedElement
         );
     }
 
+    /**
+     * @return CollectionVO
+     */
+    public function getCollection()
+    {
+        return $this->collectionVO;
+    }
+
     /**
      * @return CollectionReference
      */
@@ -642,6 +650,8 @@ class collection implements ThumbnailedElement
         $this->collectionService->delete($this->databox, $this->collectionVO, $this->reference);
 
         $this->getCollectionRepository()->delete($this->collectionVO);
+
+        $this->app['manipulator.registration']->deleteRegistrationsOnCollection($this);
         $this->app['repo.collections-registry']->purgeRegistry();
     }
 
@@ -654,6 +664,8 @@ class collection implements ThumbnailedElement
         $this->collectionService->unmountCollection($this->reference);
 
         $this->getReferenceRepository()->delete($this->reference);
+
+        $this->app['manipulator.registration']->deleteRegistrationsOnCollection($this);
         $this->app['repo.collections-registry']->purgeRegistry();
 
         return $this;
diff --git a/lib/classes/phrasea.php b/lib/classes/phrasea.php
index 1b1f6faa83..c907c13ba6 100644
--- a/lib/classes/phrasea.php
+++ b/lib/classes/phrasea.php
@@ -10,6 +10,8 @@
  */
 
 use Alchemy\Phrasea\Application;
+use Alchemy\Phrasea\Collection\CollectionRepositoryRegistry;
+use Alchemy\Phrasea\Collection\Reference\CollectionReferenceRepository;
 use Symfony\Component\Translation\TranslatorInterface;
 
 class phrasea
@@ -98,49 +100,28 @@ class phrasea
 
     public static function sbasFromBas(Application $app, $base_id)
     {
-        if (!self::$_bas2sbas) {
-            try {
-                $data = $app->getApplicationBox()->get_data_from_cache(self::CACHE_SBAS_FROM_BAS);
-                if (!$data) {
-                    throw new \Exception('Could not get sbas from cache');
-                }
-                self::$_bas2sbas = $data;
-            } catch (\Exception $e) {
-                $sql = 'SELECT base_id, sbas_id FROM bas';
-                $stmt = $app->getApplicationBox()->get_connection()->prepare($sql);
-                $stmt->execute();
-                $rs = $stmt->fetchAll(PDO::FETCH_ASSOC);
-                $stmt->closeCursor();
+        /** @var CollectionReferenceRepository $repository */
+        $repository = $app['repo.collection-references'];
+        $reference = $repository->find($base_id);
 
-                foreach ($rs as $row) {
-                    self::$_bas2sbas[$row['base_id']] = (int) $row['sbas_id'];
-                }
-
-                $app->getApplicationBox()->set_data_to_cache(self::$_bas2sbas, self::CACHE_SBAS_FROM_BAS);
-            }
+        if ($reference) {
+            return $reference->getDataboxId();
         }
 
-        return isset(self::$_bas2sbas[$base_id]) ? self::$_bas2sbas[$base_id] : false;
+        return false;
     }
 
     public static function baseFromColl($sbas_id, $coll_id, Application $app)
     {
-        if (!self::$_coll2bas) {
-            $conn = $app->getApplicationBox()->get_connection();
-            $sql = 'SELECT base_id, server_coll_id, sbas_id FROM bas';
-            $stmt = $conn->prepare($sql);
-            $stmt->execute();
-            $rs = $stmt->fetchAll(PDO::FETCH_ASSOC);
-            $stmt->closeCursor();
+        /** @var CollectionReferenceRepository $repository */
+        $repository = $app['repo.collection-references'];
+        $reference = $repository->findByCollectionId($sbas_id, $coll_id);
 
-            foreach ($rs as $row) {
-                if (!isset(self::$_coll2bas[$row['sbas_id']]))
-                    self::$_coll2bas[$row['sbas_id']] = [];
-                self::$_coll2bas[$row['sbas_id']][$row['server_coll_id']] = (int) $row['base_id'];
-            }
+        if ($reference) {
+            return $reference->getBaseId();
         }
 
-        return isset(self::$_coll2bas[$sbas_id][$coll_id]) ? self::$_coll2bas[$sbas_id][$coll_id] : false;
+        return false;
     }
 
     public static function reset_baseDatas(appbox $appbox)
@@ -175,20 +156,15 @@ class phrasea
 
     public static function collFromBas(Application $app, $base_id)
     {
-        if (!self::$_bas2coll) {
-            $conn = $app->getApplicationBox()->get_connection();
-            $sql = 'SELECT base_id, server_coll_id FROM bas';
-            $stmt = $conn->prepare($sql);
-            $stmt->execute();
-            $rs = $stmt->fetchAll(PDO::FETCH_ASSOC);
-            $stmt->closeCursor();
+        /** @var CollectionReferenceRepository $repository */
+        $repository = $app['repo.collection-references'];
+        $reference = $repository->find($base_id);
 
-            foreach ($rs as $row) {
-                self::$_bas2coll[$row['base_id']] = (int) $row['server_coll_id'];
-            }
+        if ($reference) {
+            return $reference->getCollectionId();
         }
 
-        return isset(self::$_bas2coll[$base_id]) ? self::$_bas2coll[$base_id] : false;
+        return false;
     }
 
     public static function sbas_names($sbas_id, Application $app)
@@ -234,27 +210,28 @@ class phrasea
 
     public static function bas_labels($base_id, Application $app)
     {
-        if (!self::$_bas_labels) {
-            try {
-                self::$_bas_labels = $app->getApplicationBox()->get_data_from_cache(self::CACHE_BAS_LABELS);
-            } catch (\Exception $e) {
-                foreach ($app->getDataboxes() as $databox) {
-                    foreach ($databox->get_collections() as $collection) {
-                        self::$_bas_labels[$collection->get_base_id()] = [
-                            'fr' => $collection->get_label('fr'),
-                            'en' => $collection->get_label('en'),
-                            'de' => $collection->get_label('de'),
-                            'nl' => $collection->get_label('nl'),
-                        ];
-                    }
-                }
+        /** @var CollectionReferenceRepository $repository */
+        $referenceRepository = $app['repo.collection-references'];
+        $reference = $referenceRepository->find($base_id);
 
-                $app->getApplicationBox()->set_data_to_cache(self::$_bas_labels, self::CACHE_BAS_LABELS);
-            }
+        if (! $reference) {
+            return 'Unknown collection';
         }
 
-        if (isset(self::$_bas_labels[$base_id]) && isset(self::$_bas_labels[$base_id][$app['locale']])) {
-            return self::$_bas_labels[$base_id][$app['locale']];
+        /** @var CollectionRepositoryRegistry $collectionRepositoryRegistry */
+        $collectionRepositoryRegistry = $app['repo.collections-registry'];
+        $collectionRepository = $collectionRepositoryRegistry->getRepositoryByDatabox($reference->getDataboxId());
+
+        $collection = $collectionRepository->find($reference->getCollectionId());
+
+        if (! $collection) {
+            throw new \RuntimeException('Missing collection ' . $base_id . '.');
+        }
+
+        $labels = $collection->getCollection()->getLabels();
+
+        if (isset($labels[$app['locale']])) {
+            return $labels[$app['locale']];
         }
 
         return 'Unknown collection';