diff --git a/modules/system/system.install b/modules/system/system.install
index 60d5046d739..028a0bdb6fc 100644
--- a/modules/system/system.install
+++ b/modules/system/system.install
@@ -935,7 +935,11 @@ function system_schema() {
         'not null' => FALSE)
       ),
     'primary key' => array('filename'),
-    'indexes' => array('weight' => array('weight')),
+    'indexes' => 
+      array(
+        'modules' => array(array('type', 12), 'status', 'weight', 'filename'),
+        'bootstrap' => array(array('type', 12), 'status', 'bootstrap', 'weight', 'filename'),
+      ),
     );
 
   $schema['url_alias'] = array(
@@ -4443,6 +4447,17 @@ function system_update_6034() {
   return $ret;
 }
 
+/**
+ * Change index on system table for better performance.
+ */
+function system_update_6035() {
+  $ret = array();
+  db_drop_index($ret, 'system', 'weight');
+  db_add_index($ret, 'system', 'modules', array(array('type', 12), 'status', 'weight', 'filename'));
+  db_add_index($ret, 'system', 'bootstrap', array(array('type', 12), 'status', 'bootstrap', 'weight', 'filename'));
+  return $ret;
+}
+
 /**
  * @} End of "defgroup updates-5.x-to-6.x"
  * The next series of updates should start at 7000.