core/modules/file/src/Tests/DownloadTest.php       |  2 +-
 .../image/src/Tests/ImageStylesPathAndUrlTest.php  |  2 +-
 .../src/Tests/d6/MigrateSystemPerformanceTest.php  |  1 -
 .../page_cache/src/StackMiddleware/PageCache.php   | 14 ------
 .../modules/page_cache/src/Tests/PageCacheTest.php | 53 ----------------------
 .../system/config/install/system.performance.yml   |  2 -
 core/modules/system/src/Form/PerformanceForm.php   | 11 -----
 .../system/src/Tests/Session/SessionTest.php       |  2 +-
 8 files changed, 3 insertions(+), 84 deletions(-)

diff --git a/core/modules/file/src/Tests/DownloadTest.php b/core/modules/file/src/Tests/DownloadTest.php
index 130b07c..4df65e5 100644
--- a/core/modules/file/src/Tests/DownloadTest.php
+++ b/core/modules/file/src/Tests/DownloadTest.php
@@ -56,7 +56,7 @@ public function testPrivateFileTransferWithoutPageCache() {
    */
   public function testPrivateFileTransferWithPageCache() {
     // Turn on page caching and rerun the test.
-    $this->assertTrue($this->container->get('module_installer')->install(['page_cache']), 'Page cache module installed.');
+    $this->container->get('module_installer')->install(['page_cache']);
     $config = $this->config('system.performance');
     $config->set('cache.page.max_age', 300);
     $config->save();
diff --git a/core/modules/image/src/Tests/ImageStylesPathAndUrlTest.php b/core/modules/image/src/Tests/ImageStylesPathAndUrlTest.php
index ebaa81c..88cf620 100644
--- a/core/modules/image/src/Tests/ImageStylesPathAndUrlTest.php
+++ b/core/modules/image/src/Tests/ImageStylesPathAndUrlTest.php
@@ -247,7 +247,7 @@ function doImageStyleUrlAndPathTests($scheme, $clean_url = TRUE, $extra_slash =
    */
   protected function enablePageCache() {
     // Turn on page caching and rerun the test.
-    $this->assertTrue($this->container->get('module_installer')->install(['page_cache']), 'Page cache module installed.');
+    $this->container->get('module_installer')->install(['page_cache']);
     $config = $this->config('system.performance');
     $config->set('cache.page.max_age', 300);
     $config->save();
diff --git a/core/modules/migrate_drupal/src/Tests/d6/MigrateSystemPerformanceTest.php b/core/modules/migrate_drupal/src/Tests/d6/MigrateSystemPerformanceTest.php
index 50d6c51..933ccb7 100644
--- a/core/modules/migrate_drupal/src/Tests/d6/MigrateSystemPerformanceTest.php
+++ b/core/modules/migrate_drupal/src/Tests/d6/MigrateSystemPerformanceTest.php
@@ -40,7 +40,6 @@ public function testSystemPerformance() {
     $this->assertIdentical($config->get('css.preprocess'), FALSE);
     $this->assertIdentical($config->get('js.preprocess'), FALSE);
     $this->assertIdentical($config->get('cache.page.max_age'), 0);
-    $this->assertIdentical($config->get('response.gzip'), TRUE);
   }
 
 }
diff --git a/core/modules/page_cache/src/StackMiddleware/PageCache.php b/core/modules/page_cache/src/StackMiddleware/PageCache.php
index 60afa5d..66a5f88 100644
--- a/core/modules/page_cache/src/StackMiddleware/PageCache.php
+++ b/core/modules/page_cache/src/StackMiddleware/PageCache.php
@@ -231,20 +231,6 @@ protected function fetch(Request $request, $type = self::MASTER_REQUEST, $catch
       return $response;
     }
 
-    // Check if the current page may be compressed.
-    if (extension_loaded('zlib') && !$response->headers->get('Content-Encoding') && $this->config('system.performance')->get('response.gzip')) {
-      $content = $response->getContent();
-      if ($content) {
-        $response->setContent(gzencode($content, 9, FORCE_GZIP));
-        $response->headers->set('Content-Encoding', 'gzip');
-      }
-
-      // When page compression is enabled, ensure that proxy caches will record
-      // and deliver different versions of a page depending on whether the
-      // client supports gzip or not.
-      $response->setVary('Accept-Encoding', FALSE);
-    }
-
     // Use the actual timestamp from an Expires header, if available.
     $date = $response->getExpires();
     $expire = ($date > (new \DateTime())) ? $date->getTimestamp() : Cache::PERMANENT;
diff --git a/core/modules/page_cache/src/Tests/PageCacheTest.php b/core/modules/page_cache/src/Tests/PageCacheTest.php
index 0aef91f..8e59765 100644
--- a/core/modules/page_cache/src/Tests/PageCacheTest.php
+++ b/core/modules/page_cache/src/Tests/PageCacheTest.php
@@ -138,14 +138,9 @@ function testConditionalRequests() {
    * Tests cache headers.
    */
   function testPageCache() {
-    $config = $this->config('system.performance');
-    $config->set('response.gzip', 1);
-    $config->save();
-
     // Fill the cache.
     $this->drupalGet('system-test/set-header', array('query' => array('name' => 'Foo', 'value' => 'bar')));
     $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'MISS', 'Page was not cached.');
-    $this->assertEqual(strtolower($this->drupalGetHeader('Vary')), 'cookie,accept-encoding', 'Vary header was sent.');
     // Symfony's Response logic determines a specific order for the subvalues
     // of the Cache-Control header, even if they are explicitly passed in to
     // the response header bag in a different order.
@@ -156,7 +151,6 @@ function testPageCache() {
     // Check cache.
     $this->drupalGet('system-test/set-header', array('query' => array('name' => 'Foo', 'value' => 'bar')));
     $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'HIT', 'Page was cached.');
-    $this->assertEqual(strtolower($this->drupalGetHeader('Vary')), 'cookie,accept-encoding', 'Vary: Cookie header was sent.');
     $this->assertEqual($this->drupalGetHeader('Cache-Control'), 'max-age=300, public', 'Cache-Control header was sent.');
     $this->assertEqual($this->drupalGetHeader('Expires'), 'Sun, 19 Nov 1978 05:00:00 GMT', 'Expires header was sent.');
     $this->assertEqual($this->drupalGetHeader('Foo'), 'bar', 'Custom header was sent.');
@@ -165,14 +159,12 @@ function testPageCache() {
     $this->drupalGet('system-test/set-header', array('query' => array('name' => 'Expires', 'value' => 'Fri, 19 Nov 2008 05:00:00 GMT')));
     $this->assertEqual($this->drupalGetHeader('Expires'), 'Fri, 19 Nov 2008 05:00:00 GMT', 'Default header was replaced.');
     $this->drupalGet('system-test/set-header', array('query' => array('name' => 'Vary', 'value' => 'User-Agent')));
-    $this->assertEqual(strtolower($this->drupalGetHeader('Vary')), 'user-agent,accept-encoding', 'Default header was replaced.');
 
     // Check that authenticated users bypass the cache.
     $user = $this->drupalCreateUser();
     $this->drupalLogin($user);
     $this->drupalGet('system-test/set-header', array('query' => array('name' => 'Foo', 'value' => 'bar')));
     $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'), 'Caching was bypassed.');
-    $this->assertTrue(strpos(strtolower($this->drupalGetHeader('Vary')), 'cookie') === FALSE, 'Vary: Cookie header was not sent.');
     $this->assertEqual($this->drupalGetHeader('Cache-Control'), 'must-revalidate, no-cache, post-check=0, pre-check=0, private', 'Cache-Control header was sent.');
     $this->assertEqual($this->drupalGetHeader('Expires'), 'Sun, 19 Nov 1978 05:00:00 GMT', 'Expires header was sent.');
     $this->assertEqual($this->drupalGetHeader('Foo'), 'bar', 'Custom header was sent.');
@@ -199,49 +191,4 @@ public function testPageCacheWithoutVaryCookie() {
     $this->assertTrue(strpos($this->drupalGetHeader('Vary'), 'Cookie') === FALSE, 'Vary: Cookie header was not sent.');
   }
 
-  /**
-   * Tests page compression.
-   *
-   * The test should pass even if zlib.output_compression is enabled in php.ini,
-   * .htaccess or similar, or if compression is done outside PHP, e.g. by the
-   * mod_deflate Apache module.
-   */
-  function testPageCompression() {
-    $config = $this->config('system.performance');
-    $config->set('response.gzip', 1);
-    $config->save();
-
-    // Fill the cache and verify that output is compressed.
-    $this->drupalGet('', array(), array('Accept-Encoding: gzip,deflate'));
-    $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'MISS', 'Page was not cached.');
-    $this->drupalSetContent(gzinflate(substr($this->drupalGetContent(), 10, -8)));
-    $this->assertRaw('</html>', 'Page was gzip compressed.');
-
-    // Verify that cached output is compressed.
-    $this->drupalGet('', array(), array('Accept-Encoding: gzip,deflate'));
-    $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'HIT', 'Page was cached.');
-    $this->assertEqual($this->drupalGetHeader('Content-Encoding'), 'gzip', 'A Content-Encoding header was sent.');
-    $this->drupalSetContent(gzinflate(substr($this->drupalGetContent(), 10, -8)));
-    $this->assertRaw('</html>', 'Page was gzip compressed.');
-
-    // Verify that a client without compression support gets an uncompressed page.
-    $this->drupalGet('');
-    $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'HIT', 'Page was cached.');
-    $this->assertFalse($this->drupalGetHeader('Content-Encoding'), 'A Content-Encoding header was not sent.');
-    $this->assertTitle(t('Test page | @site-name', array('@site-name' => $this->config('system.site')->get('name'))), 'Site title matches.');
-    $this->assertRaw('</html>', 'Page was not compressed.');
-
-    // Disable compression mode.
-    $config->set('response.gzip', 0);
-    $config->save();
-
-    // Verify if cached page is still available for a client with compression support.
-    $this->drupalGet('', array(), array('Accept-Encoding: gzip,deflate'));
-    $this->drupalSetContent(gzinflate(substr($this->drupalGetContent(), 10, -8)));
-    $this->assertRaw('</html>', 'Page was delivered after compression mode is changed (compression support enabled).');
-
-    // Verify if cached page is still available for a client without compression support.
-    $this->drupalGet('');
-    $this->assertRaw('</html>', 'Page was delivered after compression mode is changed (compression support disabled).');
-  }
 }
diff --git a/core/modules/system/config/install/system.performance.yml b/core/modules/system/config/install/system.performance.yml
index 058f9e8..11392bd 100644
--- a/core/modules/system/config/install/system.performance.yml
+++ b/core/modules/system/config/install/system.performance.yml
@@ -12,6 +12,4 @@ fast_404:
 js:
   preprocess: true
   gzip: true
-response:
-  gzip: false
 stale_file_threshold: 2592000
diff --git a/core/modules/system/src/Form/PerformanceForm.php b/core/modules/system/src/Form/PerformanceForm.php
index e007df9..c5eb48c 100644
--- a/core/modules/system/src/Form/PerformanceForm.php
+++ b/core/modules/system/src/Form/PerformanceForm.php
@@ -151,16 +151,6 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       '#description' => t('External resources can be optimized automatically, which can reduce both the size and number of requests made to your website.') . $disabled_message,
     );
 
-    $form['bandwidth_optimization']['page_compression'] = array(
-      '#type' => 'checkbox',
-      '#title' => t('Compress cached pages'),
-      '#default_value' => $config->get('response.gzip'),
-      '#states' => array(
-        'visible' => array(
-          'input[name="cache"]' => array('checked' => TRUE),
-        ),
-      ),
-    );
     $form['bandwidth_optimization']['preprocess_css'] = array(
       '#type' => 'checkbox',
       '#title' => t('Aggregate CSS files'),
@@ -190,7 +180,6 @@ public function submitForm(array &$form, FormStateInterface $form_state) {
 
     $this->config('system.performance')
       ->set('cache.page.max_age', $form_state->getValue('page_cache_maximum_age'))
-      ->set('response.gzip', $form_state->getValue('page_compression'))
       ->set('css.preprocess', $form_state->getValue('preprocess_css'))
       ->set('js.preprocess', $form_state->getValue('preprocess_js'))
       ->save();
diff --git a/core/modules/system/src/Tests/Session/SessionTest.php b/core/modules/system/src/Tests/Session/SessionTest.php
index 95eae11..d6cea95 100644
--- a/core/modules/system/src/Tests/Session/SessionTest.php
+++ b/core/modules/system/src/Tests/Session/SessionTest.php
@@ -144,7 +144,7 @@ function testEmptyAnonymousSession() {
     $this->assertSessionEmpty(TRUE);
 
     // The same behavior is expected when caching is enabled.
-    $this->assertTrue($this->container->get('module_installer')->install(['page_cache']), 'Page cache module installed.');
+    $this->container->get('module_installer')->install(['page_cache']);
     $config = $this->config('system.performance');
     $config->set('cache.page.max_age', 300);
     $config->save();