diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/Bundle/TestBundle/Controller/SessionController.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/Bundle/TestBundle/Controller/SessionController.php
index a1d91e7929..0c82d8cc73 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/Bundle/TestBundle/Controller/SessionController.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/Bundle/TestBundle/Controller/SessionController.php
@@ -43,6 +43,14 @@ class SessionController implements ContainerAwareInterface
         return new Response(sprintf('Welcome back %s, nice to meet you.', $name));
     }
 
+    public function cacheableAction()
+    {
+        $response = new Response('all good');
+        $response->setSharedMaxAge(100);
+
+        return $response;
+    }
+
     public function logoutAction(Request $request)
     {
         $request->getSession()->invalidate();
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/Bundle/TestBundle/Resources/config/routing.yml b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/Bundle/TestBundle/Resources/config/routing.yml
index 11b85a86d3..923204ab0f 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/Bundle/TestBundle/Resources/config/routing.yml
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/Bundle/TestBundle/Resources/config/routing.yml
@@ -2,6 +2,10 @@ session_welcome:
     path:     /session
     defaults: { _controller: TestBundle:Session:welcome }
 
+session_cacheable:
+    path:     /cacheable
+    defaults: { _controller: Symfony\Bundle\FrameworkBundle\Tests\Functional\Bundle\TestBundle\Controller\SessionController::cacheableAction }
+
 session_welcome_name:
     path:     /session/{name}
     defaults: { _controller: TestBundle:Session:welcome }
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/SessionTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/SessionTest.php
index 166d8a3391..2e1634220c 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/SessionTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/SessionTest.php
@@ -126,6 +126,22 @@ class SessionTest extends WebTestCase
         $this->assertContains('Welcome back client2, nice to meet you.', $crawler2->text());
     }
 
+    /**
+     * @dataProvider getConfigs
+     */
+    public function testCorrectCacheControlHeadersForCacheableAction($config, $insulate)
+    {
+        $client = $this->createClient(array('test_case' => 'Session', 'root_config' => $config));
+        if ($insulate) {
+            $client->insulate();
+        }
+
+        $client->request('GET', '/cacheable');
+
+        $response = $client->getResponse();
+        $this->assertSame('public, s-maxage=100', $response->headers->get('cache-control'));
+    }
+
     public function getConfigs()
     {
         return array(
diff --git a/src/Symfony/Component/HttpFoundation/Session/Session.php b/src/Symfony/Component/HttpFoundation/Session/Session.php
index f0379c1697..c0978d552f 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Session.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Session.php
@@ -54,8 +54,6 @@ class Session implements SessionInterface, \IteratorAggregate, \Countable
      */
     public function start()
     {
-        ++$this->usageIndex;
-
         return $this->storage->start();
     }
 
@@ -160,7 +158,9 @@ class Session implements SessionInterface, \IteratorAggregate, \Countable
      */
     public function isEmpty()
     {
-        ++$this->usageIndex;
+        if ($this->isStarted()) {
+            ++$this->usageIndex;
+        }
         foreach ($this->data as &$data) {
             if (!empty($data)) {
                 return false;
@@ -185,8 +185,6 @@ class Session implements SessionInterface, \IteratorAggregate, \Countable
      */
     public function migrate($destroy = false, $lifetime = null)
     {
-        ++$this->usageIndex;
-
         return $this->storage->regenerate($destroy, $lifetime);
     }
 
@@ -195,8 +193,6 @@ class Session implements SessionInterface, \IteratorAggregate, \Countable
      */
     public function save()
     {
-        ++$this->usageIndex;
-
         $this->storage->save();
     }
 
diff --git a/src/Symfony/Component/HttpFoundation/Session/SessionBagProxy.php b/src/Symfony/Component/HttpFoundation/Session/SessionBagProxy.php
index 88005ee092..3504bdfe7b 100644
--- a/src/Symfony/Component/HttpFoundation/Session/SessionBagProxy.php
+++ b/src/Symfony/Component/HttpFoundation/Session/SessionBagProxy.php
@@ -44,6 +44,9 @@ final class SessionBagProxy implements SessionBagInterface
      */
     public function isEmpty()
     {
+        if (!isset($this->data[$this->bag->getStorageKey()])) {
+            return true;
+        }
         ++$this->usageIndex;
 
         return empty($this->data[$this->bag->getStorageKey()]);
@@ -81,8 +84,6 @@ final class SessionBagProxy implements SessionBagInterface
      */
     public function clear()
     {
-        ++$this->usageIndex;
-
         return $this->bag->clear();
     }
 }
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php b/src/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php
index 12e32df36a..bfe13f05ed 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php
@@ -407,8 +407,6 @@ class NativeSessionStorage implements SessionStorageInterface
         }
 
         if ($this->saveHandler instanceof SessionHandlerProxy) {
-            session_set_save_handler($this->saveHandler->getHandler(), false);
-        } elseif ($this->saveHandler instanceof \SessionHandlerInterface) {
             session_set_save_handler($this->saveHandler, false);
         }
     }
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/Proxy/SessionHandlerProxy.php b/src/Symfony/Component/HttpFoundation/Session/Storage/Proxy/SessionHandlerProxy.php
index 53c1209a1c..b11cc397a0 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/Proxy/SessionHandlerProxy.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/Proxy/SessionHandlerProxy.php
@@ -14,7 +14,7 @@ namespace Symfony\Component\HttpFoundation\Session\Storage\Proxy;
 /**
  * @author Drak <drak@zikula.org>
  */
-class SessionHandlerProxy extends AbstractProxy implements \SessionHandlerInterface
+class SessionHandlerProxy extends AbstractProxy implements \SessionHandlerInterface, \SessionUpdateTimestampHandlerInterface
 {
     protected $handler;
 
@@ -82,4 +82,20 @@ class SessionHandlerProxy extends AbstractProxy implements \SessionHandlerInterf
     {
         return (bool) $this->handler->gc($maxlifetime);
     }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function validateId($sessionId)
+    {
+        return !$this->handler instanceof \SessionUpdateTimestampHandlerInterface || $this->handler->validateId($sessionId);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function updateTimestamp($sessionId, $data)
+    {
+        return $this->handler instanceof \SessionUpdateTimestampHandlerInterface ? $this->handler->updateTimestamp($sessionId, $data) : $this->write($sessionId, $data);
+    }
 }
diff --git a/src/Symfony/Component/HttpFoundation/Tests/Session/Storage/Proxy/SessionHandlerProxyTest.php b/src/Symfony/Component/HttpFoundation/Tests/Session/Storage/Proxy/SessionHandlerProxyTest.php
index 682825356a..0b48250e01 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/Session/Storage/Proxy/SessionHandlerProxyTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/Session/Storage/Proxy/SessionHandlerProxyTest.php
@@ -121,4 +121,37 @@ class SessionHandlerProxyTest extends TestCase
 
         $this->proxy->gc(86400);
     }
+
+    /**
+     * @requires PHPUnit 5.1
+     */
+    public function testValidateId()
+    {
+        $mock = $this->getMockBuilder(array('SessionHandlerInterface', 'SessionUpdateTimestampHandlerInterface'))->getMock();
+        $mock->expects($this->once())
+            ->method('validateId');
+
+        $proxy = new SessionHandlerProxy($mock);
+        $proxy->validateId('id');
+
+        $this->assertTrue($this->proxy->validateId('id'));
+    }
+
+    /**
+     * @requires PHPUnit 5.1
+     */
+    public function testUpdateTimestamp()
+    {
+        $mock = $this->getMockBuilder(array('SessionHandlerInterface', 'SessionUpdateTimestampHandlerInterface'))->getMock();
+        $mock->expects($this->once())
+            ->method('updateTimestamp');
+
+        $proxy = new SessionHandlerProxy($mock);
+        $proxy->updateTimestamp('id', 'data');
+
+        $this->mock->expects($this->once())
+            ->method('write');
+
+        $this->proxy->updateTimestamp('id', 'data');
+    }
 }