diff --git a/CHANGELOG.txt b/CHANGELOG.txt
index bf9a6f82ad2aa686dad8be08de8186858e79fe94..58ff4057fa3325c918b515583028c95ced0c6c34 100644
--- a/CHANGELOG.txt
+++ b/CHANGELOG.txt
@@ -28,6 +28,7 @@ Views 2.x-dev
     o #674772 by joachim: Unable to distinguish profile.module fields with same name in different profile categories.
     o #727798 by SteveReher: Fix typo in overrides.html documentation.
     o #621980 by yhahn: Namespace tabs.js to guarantee no conflicts with jQuery UI.
+    o #684656 by yhahn: Prevent Views from performing an unneeded variable_set() during block list.
   
   Other changes:
     o #570558 by yhahn: Segment default views caching to conserve memory used by Views during normal operation.
diff --git a/views.module b/views.module
index ee5e22dd597a8bd84ad405acc90c565a37de950d..002becfdbdeb38aaad7d5f8aed0db015ac6ee8ab 100644
--- a/views.module
+++ b/views.module
@@ -349,7 +349,11 @@ function views_block($op = 'list', $delta = 0, $edit = array()) {
         }
       }
 
-      variable_set('views_block_hashes', $hashes);
+      // Only save hashes if they have changed.
+      $old_hashes = variable_get('views_block_hashes', array());
+      if ($hashes != $old_hashes) {
+        variable_set('views_block_hashes', $hashes);
+      }
       // Save memory: Destroy those views.
       foreach ($views as $view) {
         $view->destroy();