diff --git a/core/modules/forum/src/ForumManager.php b/core/modules/forum/src/ForumManager.php
index aa7f2b19af..85f8c00761 100644
--- a/core/modules/forum/src/ForumManager.php
+++ b/core/modules/forum/src/ForumManager.php
@@ -327,48 +327,78 @@ protected function lastVisit($nid, AccountInterface $account) {
    *
    * @return \stdClass
    *   The last post for the given forum.
+   *
+   * @deprecated in Drupal 8.0.0 and will be removed before Drupal 9.0.0.
+   *   Use getLastPostData() instead
    */
   protected function getLastPost($tid) {
     if (!empty($this->lastPostData[$tid])) {
       return $this->lastPostData[$tid];
     }
-    // Query "Last Post" information for this forum. Only add the node table to
-    // the query if this is necessary for filtering access-restricted records.
-    if ($this->currentUserCanViewAllNodes()) {
-      $query = $this->connection->select('forum_index', 'f');
-    }
-    else {
-      $query = $this->connection->select('node', 'n')
-        ->addTag('node_access');
-      $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('COALESCE(ces.last_comment_name, u.name)', 'last_comment_name');
+    $data = $this->getLastPostData([$tid]);
+    return reset($data);
+  }
 
-    $topic = $query
-      ->fields('ces', ['last_comment_timestamp', 'last_comment_uid'])
-      ->condition('f.tid', $tid)
-      ->orderBy('f.last_comment_timestamp', 'DESC')
-      ->range(0, 1)
-      ->execute()
-      ->fetchObject();
-
-    // Build the last post information.
-    $last_post = new \stdClass();
-    if (!empty($topic->last_comment_timestamp)) {
-      $last_post->created = $topic->last_comment_timestamp;
-      $last_post->name = $topic->last_comment_name;
-      $last_post->uid = $topic->last_comment_uid;
+  /**
+   * Provides the last post information for the given forum tids.
+   *
+   * @param int[] $tids
+   *   The forum tids.
+   *
+   * @return \stdClass[]
+   *   The last post information for the given forums.
+   */
+  protected function getLastPostData(array $tids) {
+    // Check if all tids already have post info. We assume no duplicate tids.
+    $tids_as_keys = array_flip($tids);
+    $known_data = array_intersect_key($this->lastPostData, $tids_as_keys);
+    if (count($known_data) < count($tids)) {
+      $unknown_tids = array_diff($tids, array_keys($this->lastPostData));
+
+      // Query "Last Post" information. Only add the node table to the query if
+      // this is necessary for filtering access-restricted records.
+      if ($this->currentUserCanViewAllNodes()) {
+        $query = $this->connection->select('forum_index', 'f');
+      }
+      else {
+        $query = $this->connection->select('node', 'n')
+          ->addTag('node_access');
+        $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->addField('f', 'tid');
+      $query->addExpression('COALESCE(ces.last_comment_name, u.name)', 'last_comment_name');
+
+      $topics = $query
+        ->fields('ces', ['last_comment_timestamp', 'last_comment_uid'])
+        ->condition('f.tid', $unknown_tids, 'IN')
+        ->orderBy('f.last_comment_timestamp', 'DESC')
+        ->range(0, 1)
+        ->execute()
+        ->fetchAllAssoc('tid');
+
+      // Build the last post information.
+      foreach ($unknown_tids as $tid) {
+        $this->lastPostData[$tid] = new \stdClass();
+        if (!empty($topics[$tid]->last_comment_timestamp)) {
+          $this->lastPostData[$tid]->created = $topics[$tid]->last_comment_timestamp;
+          $this->lastPostData[$tid]->name = $topics[$tid]->last_comment_name;
+          $this->lastPostData[$tid]->uid = $topics[$tid]->last_comment_uid;
+        }
+      }
+
+      $known_data = array_intersect_key($this->lastPostData, $tids_as_keys);
     }
 
-    $this->lastPostData[$tid] = $last_post;
-    return $last_post;
+    return $known_data;
   }
 
   /**
    * Provides statistics for a forum.
    *
+   * This will prime statistics for all known forums, to minimize queries.
+   *
    * @param int $tid
    *   The forum tid.
    *
@@ -425,6 +455,15 @@ public function getChildren($vid, $tid) {
     }
     $forums = [];
     $_forums = $this->entityManager->getStorage('taxonomy_term')->loadTree($vid, $tid, NULL, TRUE);
+
+    // Prime last post details for the forums. Unlike getForumStatistics() we
+    // only query data for the forums we actually need.
+    $tids = [];
+    foreach ($_forums as $forum) {
+      $tids[] = $forum->id();
+    }
+    $last_post_data = $this->getLastPostData($tids);
+
     foreach ($_forums as $forum) {
       // Merge in the topic and post counters.
       if (($count = $this->getForumStatistics($forum->id()))) {
@@ -437,7 +476,7 @@ public function getChildren($vid, $tid) {
       }
 
       // Merge in last post details.
-      $forum->last_post = $this->getLastPost($forum->id());
+      $forum->last_post = $last_post_data[$forum->id()];
       $forums[$forum->id()] = $forum;
     }