diff --git a/core/lib/Drupal/Component/Discovery/YamlDiscovery.php b/core/lib/Drupal/Component/Discovery/YamlDiscovery.php
index 4d00f44..ae9137b 100644
--- a/core/lib/Drupal/Component/Discovery/YamlDiscovery.php
+++ b/core/lib/Drupal/Component/Discovery/YamlDiscovery.php
@@ -49,8 +49,16 @@ public function findAll() {
     $all = array();
     foreach ($this->findFiles() as $provider => $file) {
       // If a file is empty or its contents are commented out, return an empty
-      // array instead of NULL for type consistency.
-      $all[$provider] = Yaml::decode(file_get_contents($file)) ?: array();
+      // array instead of NULL for type consistency. Do not use a ternary
+      // operator, as those can become very slow with large amounts of data. See
+      // http://fabien.potencier.org/article/48/the-php-ternary-operator-fast-or-not.
+      $contents = Yaml::decode(file_get_contents($file));
+      if (!is_null($contents)) {
+        $all[$provider] = $contents;
+      }
+      else {
+        $all[$provider] = [];
+      }
     }
 
     return $all;