diff -u b/core/modules/locale/lib/Drupal/locale/LocaleProjectStorage.php b/core/modules/locale/lib/Drupal/locale/LocaleProjectStorage.php
--- b/core/modules/locale/lib/Drupal/locale/LocaleProjectStorage.php
+++ b/core/modules/locale/lib/Drupal/locale/LocaleProjectStorage.php
@@ -29,6 +29,13 @@
   protected $cache = array();
 
   /**
+   * Cache status flag.
+   *
+   * @var bool
+   */
+  protected static $all = FALSE;
+
+  /**
    * Constructs a State object.
    *
    * @param \Drupal\Core\KeyValueStore\KeyValueFactoryInterface $key_value_factory
@@ -68,7 +75,7 @@
       foreach ($load as $key) {
         // If we find a value, even one that is NULL, add it to the cache and
         // return it.
-        if (isset($loaded_values[$key]) || array_key_exists($key, $loaded_values)) {
+        if (isset($loaded_values[$key])) {
           $values[$key] = $loaded_values[$key];
           $this->cache[$key] = $loaded_values[$key];
         }
@@ -85,8 +92,7 @@
    * {@inheritdoc}
    */
   public function set($key, $value) {
-    $this->cache[$key] = $value;
-    $this->keyValueStore->set($key, $value);
+    $this->setMultiple(array($key => $value));
   }
 
   /**
@@ -111,7 +117,7 @@
    */
   public function deleteMultiple(array $keys) {
     foreach ($keys as $key) {
-      unset($this->cache[$key]);
+      $this->cache[$key] = NULL;
     }
     $this->keyValueStore->deleteMultiple($keys);
   }
@@ -121,14 +127,15 @@
    */
   public function resetCache() {
     $this->cache = array();
+    static::$all = FALSE;
   }
 
   /**
    * {@inheritdoc}
    */
   public function deleteAll() {
-    $this->resetCache();
     $this->keyValueStore->deleteAll();
+    $this->resetCache();
   }
 
   /**
@@ -137,22 +144,30 @@
   public function disableAll() {
     $projects = $this->keyValueStore->getAll();
-    array_walk($projects, function($project){
-      $project['status'] = 0;
-    });
+    foreach ($projects as $key) {
+      $projects[$key]['status'] = 0;
+      if (isset($cache[$key])) {
+        $cache[$key] = $projects[$key];
+      }
+    }
     $this->keyValueStore->setMultiple($projects);
+
   }
 
   /**
    * {@inheritdoc}
    */
   public function countProjects() {
-    return !empty($this->cache) ? count($this->cache) : count($this->keyValueStore->getAll());
+    return count($this->getAll());
   }
 
   /**
    * {@inheritdoc}
    */
   public function getAll() {
-    return !empty($this->cache) ? $this->cache : $this->keyValueStore->getAll();
+    if (!static::$all) {
+      $this->cache = $this->keyValueStore->getAll();
+      static::$all = TRUE;
+    }
+    return $this->cache;
   }
 }