diff --git a/core/modules/forum/forum.install b/core/modules/forum/forum.install
index 4a16a8939a..c4bddebaf3 100644
--- a/core/modules/forum/forum.install
+++ b/core/modules/forum/forum.install
@@ -5,6 +5,7 @@
  * Install, update, and uninstall functions for the Forum module.
  */
 
+use Drupal\Core\Database\Database;
 use Drupal\field\Entity\FieldStorageConfig;
 use Drupal\taxonomy\Entity\Term;
 
@@ -158,6 +159,7 @@ function forum_schema() {
       'forum_topics' => ['nid', 'tid', 'sticky', 'last_comment_timestamp'],
       'created' => ['created'],
       'last_comment_timestamp' => ['last_comment_timestamp'],
+      'tid' => ['tid'],
     ],
     'foreign keys' => [
       'tracked_node' => [
@@ -175,3 +177,82 @@ function forum_schema() {
 
   return $schema;
 }
+
+/**
+ * Add cid field and index on tid to forum_index table.
+ */
+function forum_update_8400() {
+  $schema = Database::getConnection()->schema();
+  $spec = [
+    'description' => 'Maintains denormalized information about node/term relationships.',
+    'fields' => [
+      'nid' => [
+        'description' => 'The {node}.nid this record tracks.',
+        'type' => 'int',
+        'unsigned' => TRUE,
+        'not null' => TRUE,
+        'default' => 0,
+      ],
+      'title' => [
+        'description' => 'The node title.',
+        'type' => 'varchar',
+        'length' => 255,
+        'not null' => TRUE,
+        'default' => '',
+      ],
+      'tid' => [
+         'description' => 'The term ID.',
+         'type' => 'int',
+         'unsigned' => TRUE,
+         'not null' => TRUE,
+         'default' => 0,
+      ],
+      'sticky' => [
+        'description' => 'Boolean indicating whether the node is sticky.',
+        'type' => 'int',
+        'not null' => FALSE,
+        'default' => 0,
+        'size' => 'tiny',
+      ],
+      'created' => [
+        'description' => 'The Unix timestamp when the node was created.',
+        'type' => 'int',
+        'unsigned' => TRUE,
+        'not null' => TRUE,
+        'default' => 0,
+      ],
+      'last_comment_timestamp' => [
+        'type' => 'int',
+        'not null' => TRUE,
+        'default' => 0,
+        'description' => 'The Unix timestamp of the last comment that was posted within this node, from {comment}.timestamp.',
+      ],
+      'comment_count' => [
+        'type' => 'int',
+        'unsigned' => TRUE,
+        'not null' => TRUE,
+        'default' => 0,
+        'description' => 'The total number of comments on this node.',
+      ],
+    ],
+    'indexes' => [
+      'forum_topics' => ['nid', 'tid', 'sticky', 'last_comment_timestamp'],
+      'created' => ['created'],
+      'last_comment_timestamp' => ['last_comment_timestamp'],
+      'tid' => ['tid'],
+    ],
+    'foreign keys' => [
+      'tracked_node' => [
+        'table' => 'node',
+        'columns' => ['nid' => 'nid'],
+      ],
+      'term' => [
+        'table' => 'taxonomy_term_data',
+        'columns' => [
+          'tid' => 'tid',
+        ],
+      ],
+    ],
+  ];
+  $schema->addIndex('forum_index', 'tid', ['tid'], $spec);
+}
diff --git a/core/modules/forum/src/ForumIndexStorage.php b/core/modules/forum/src/ForumIndexStorage.php
index 79945746c1..d6c092e031 100644
--- a/core/modules/forum/src/ForumIndexStorage.php
+++ b/core/modules/forum/src/ForumIndexStorage.php
@@ -91,7 +91,7 @@ public function update(NodeInterface $node) {
    */
   public function updateIndex(NodeInterface $node) {
     $nid = $node->id();
-    $count = $this->database->query("SELECT COUNT(cid) FROM {comment_field_data} c INNER JOIN {forum_index} i ON c.entity_id = i.nid WHERE c.entity_id = :nid AND c.field_name = 'comment_forum' AND c.entity_type = 'node' AND c.status = :status AND c.default_langcode = 1", [
+    $count = $this->database->query("SELECT COUNT(c.cid) FROM {comment_field_data} c INNER JOIN {forum_index} i ON c.entity_id = i.nid WHERE c.entity_id = :nid AND c.field_name = 'comment_forum' AND c.entity_type = 'node' AND c.status = :status AND c.default_langcode = 1", [
       ':nid' => $nid,
       ':status' => CommentInterface::PUBLISHED,
     ])->fetchField();
diff --git a/core/modules/forum/src/ForumManager.php b/core/modules/forum/src/ForumManager.php
index 05cd860760..9ae35ea438 100644
--- a/core/modules/forum/src/ForumManager.php
+++ b/core/modules/forum/src/ForumManager.php
@@ -333,16 +333,16 @@ protected function getLastPost($tid) {
       return $this->lastPostData[$tid];
     }
     // Query "Last Post" information for this forum.
-    $query = $this->connection->select('node_field_data', 'n');
-    $query->join('forum', 'f', 'n.vid = f.vid AND f.tid = :tid', [':tid' => $tid]);
-    $query->join('comment_entity_statistics', 'ces', "n.nid = ces.entity_id AND ces.field_name = 'comment_forum' AND ces.entity_type = 'node'");
+    $query = $this->connection->select('node', 'n');
+    $query->join('forum_index', 'f', 'n.nid = f.nid');
+    $query->join('comment_entity_statistics', 'ces', "f.nid = ces.entity_id AND ces.field_name = 'comment_forum' AND ces.entity_type = 'node'");
     $query->join('users_field_data', 'u', 'ces.last_comment_uid = u.uid AND u.default_langcode = 1');
-    $query->addExpression('CASE ces.last_comment_uid WHEN 0 THEN ces.last_comment_name ELSE u.name END', 'last_comment_name');
+    $query->addExpression('COALESCE(ces.last_comment_name, u.name)', 'last_comment_name');
 
     $topic = $query
       ->fields('ces', ['last_comment_timestamp', 'last_comment_uid'])
-      ->condition('n.status', 1)
-      ->orderBy('last_comment_timestamp', 'DESC')
+      ->condition('f.tid', $tid)
+      ->orderBy('f.last_comment_timestamp', 'DESC')
       ->range(0, 1)
       ->addTag('node_access')
       ->execute()
@@ -372,16 +372,14 @@ protected function getLastPost($tid) {
   protected function getForumStatistics($tid) {
     if (empty($this->forumStatistics)) {
       // Prime the statistics.
-      $query = $this->connection->select('node_field_data', 'n');
-      $query->join('comment_entity_statistics', 'ces', "n.nid = ces.entity_id AND ces.field_name = 'comment_forum' AND ces.entity_type = 'node'");
-      $query->join('forum', 'f', 'n.vid = f.vid');
-      $query->addExpression('COUNT(n.nid)', 'topic_count');
-      $query->addExpression('SUM(ces.comment_count)', 'comment_count');
+      $query = $this->connection->select('node', 'n');
+      $query->join('forum_index', 'f', 'n.nid = f.nid');
+      $query->addExpression('COUNT(f.nid)', 'topic_count');
+      $query->addExpression('SUM(f.comment_count)', 'comment_count');
       $this->forumStatistics = $query
         ->fields('f', ['tid'])
-        ->condition('n.status', 1)
-        ->condition('n.default_langcode', 1)
         ->groupBy('tid')
+        ->orderBy('NULL')
         ->addTag('node_access')
         ->execute()
         ->fetchAllAssoc('tid');