diff --git a/src/Symfony/Component/DependencyInjection/ContainerBuilder.php b/src/Symfony/Component/DependencyInjection/ContainerBuilder.php
index 678aa37e08..512abd1d27 100644
--- a/src/Symfony/Component/DependencyInjection/ContainerBuilder.php
+++ b/src/Symfony/Component/DependencyInjection/ContainerBuilder.php
@@ -346,9 +346,11 @@ class ContainerBuilder extends Container implements TaggedContainerInterface
         try {
             if (isset($this->classReflectors[$class])) {
                 $classReflector = $this->classReflectors[$class];
-            } else {
+            } elseif ($this->trackResources) {
                 $resource = new ClassExistenceResource($class, false);
                 $classReflector = $resource->isFresh(0) ? false : new \ReflectionClass($class);
+            } else {
+                $classReflector = new \ReflectionClass($class);
             }
         } catch (\ReflectionException $e) {
             if ($throw) {