diff --git a/lib/Twig/Environment.php b/lib/Twig/Environment.php
index 49816ed9d..a5b0883ba 100644
--- a/lib/Twig/Environment.php
+++ b/lib/Twig/Environment.php
@@ -48,6 +48,7 @@ class Twig_Environment
     private $originalCache;
     private $bcWriteCacheFile = false;
     private $bcGetCacheFilename = false;
+    private $lastModifiedExtension = 0;
 
     /**
      * Constructor.
@@ -454,14 +455,16 @@ class Twig_Environment
      */
     public function isTemplateFresh($name, $time)
     {
-        foreach ($this->extensions as $extension) {
-            $r = new ReflectionObject($extension);
-            if (filemtime($r->getFileName()) > $time) {
-                return false;
+        if(0 === $this->lastModifiedExtension) {
+            foreach ($this->extensions as $extension) {
+                $r = new ReflectionObject($extension);
+                if (($extensionTime = filemtime($r->getFileName())) > $this->lastModifiedExtension) {
+                    $this->lastModifiedExtension = $extensionTime;
+                }
             }
         }
 
-        return $this->getLoader()->isFresh($name, $time);
+        return $this->lastModifiedExtension <= $time && $this->getLoader()->isFresh($name, $time);
     }
 
     /**
@@ -767,6 +770,8 @@ class Twig_Environment
             throw new LogicException(sprintf('Unable to register extension "%s" as extensions have already been initialized.', $extension->getName()));
         }
 
+        $this->lastModifiedExtension = 0;
+
         $this->extensions[$extension->getName()] = $extension;
     }