diff --git a/modules/system/system.install b/modules/system/system.install
index 6d355a244f1..06b29a83649 100644
--- a/modules/system/system.install
+++ b/modules/system/system.install
@@ -528,6 +528,7 @@ function system_install() {
         data longtext,
         PRIMARY KEY (uid),
         UNIQUE KEY name (name),
+        KEY created (created),
         KEY access (access)
       ) /*!40100 DEFAULT CHARACTER SET UTF8 */ ");
 
@@ -995,6 +996,7 @@ function system_install() {
         UNIQUE (name)
       )");
       db_query("CREATE INDEX {users}_access_idx ON {users} (access)");
+      db_query("CREATE INDEX {users}_created_idx ON {users} (created)");
 
       db_query("CREATE TABLE {users_roles} (
         uid int_unsigned NOT NULL default '0',
@@ -3485,6 +3487,35 @@ function system_update_1021() {
  */
 
 
+/**
+ * @defgroup updates-5.x-extra Extra system updates for 5.x
+ * @{
+ */
+
+/**
+ * Add index on users created column.
+ */
+function system_update_1022() {
+  $ret = array();
+  switch ($GLOBALS['db_type']) {
+    case 'mysql':
+    case 'mysqli':
+      $ret[] = update_sql('ALTER TABLE {users} ADD KEY created (created)');
+      break;
+
+    case 'pgsql':
+      $ret[] = update_sql("CREATE INDEX {users}_created_idx ON {users} (created)");
+      break;
+  }
+  // Also appears as system_update_2004(). Ensure we don't update twice.
+  variable_set('system_update_1022', TRUE);
+  return $ret;
+}
+
+/**
+ * @} End of "defgroup updates-5.x-extra"
+ */
+
 /**
  * @defgroup updates-5.0-to-x.x System updates from 5.0 to x.x
  * @{