diff --git a/phpBB/includes/functions.php b/phpBB/includes/functions.php
index 6750772ebb..820a03fe64 100644
--- a/phpBB/includes/functions.php
+++ b/phpBB/includes/functions.php
@@ -1649,11 +1649,12 @@ function get_complete_topic_tracking($forum_id, $topic_ids, $global_announce_lis
 *
 * @param int $user_id			User ID (or false for current user)
 * @param string $sql_extra		Extra WHERE SQL statement
+* @param string $sql_limit		Limits the size of unread topics list
 *
 * @return array[int][int]		Topic ids as keys, mark_time of topic as value
 * @author rxu
 */
-function get_unread_topics_list($user_id = false, $sql_extra = '')
+function get_unread_topics_list($user_id = false, $sql_extra = '', $sql_limit = 1001)
 {
 	global $config, $db, $user;
 
@@ -1667,32 +1668,18 @@ function get_unread_topics_list($user_id = false, $sql_extra = '')
 
 	if ($config['load_db_lastread'] && $user->data['is_registered'])
 	{
-		// List of the tracked forums (not ideal, hope the better way will be found)
-		// This list is to fetch later the forums user never read (fully) before
-		$sql = 'SELECT forum_id
-			FROM ' . FORUMS_TRACK_TABLE . "
-			WHERE user_id = $user_id";
-		$result = $db->sql_query($sql);
-
-		while ($row = $db->sql_fetchrow($result))
-		{
-			$tracked_forums_list[] = (int) $row['forum_id'];
-		}
-		$db->sql_freeresult($result);
-
 		// Get list of the unread topics - on topics tracking as the first step
 		$sql = 'SELECT t.topic_id, t.topic_last_post_time, tt.mark_time
 			FROM ' . TOPICS_TABLE . ' t, ' . TOPICS_TRACK_TABLE . " tt
 			WHERE t.topic_id = tt.topic_id
-				AND t.topic_last_post_time >= tt.mark_time
 				AND tt.user_id = $user_id
 			$sql_extra
 			ORDER BY t.topic_last_post_time DESC";
-		$result = $db->sql_query($sql);
+		$result = $db->sql_query_limit($sql, $sql_limit);
 
 		while ($row = $db->sql_fetchrow($result))
 		{
-			if ($row['topic_last_post_time'] == $row['mark_time'])
+			if ($row['topic_last_post_time'] <= $row['mark_time'])
 			{
 				// Check if there're read topics for the forums having unread ones
 				$read_topics_list[$row['topic_id']] = (int) $row['mark_time'];
@@ -1704,46 +1691,67 @@ function get_unread_topics_list($user_id = false, $sql_extra = '')
 		}
 		$db->sql_freeresult($result);
 
-		// Get the full list of the tracked topics
+		// Get the full list of the tracked topics and unread topics count
 		$tracked_topics_list = array_merge(array_keys($unread_topics_list), array_keys($read_topics_list));
+		$unread_list_count = sizeof($unread_topics_list);
 
-		// Get list of the unread topics - on forums tracking as the second step
-		// We don't take in account topics tracked before
-		$sql = 'SELECT t.topic_id, ft.mark_time
-			FROM ' . TOPICS_TABLE . ' t, ' . FORUMS_TRACK_TABLE . ' ft
-			WHERE t.forum_id = ft.forum_id
-				AND t.topic_last_post_time > ft.mark_time
-				AND ' . $db->sql_in_set('t.topic_id', $tracked_topics_list, true, true) . "
-				AND ft.user_id = $user_id
-			$sql_extra
-			ORDER BY t.topic_last_post_time DESC";
-		$result = $db->sql_query($sql);
-
-		while ($row = $db->sql_fetchrow($result))
+		if ($unread_list_count < $sql_limit)
 		{
-			$unread_topics_list[$row['topic_id']] = (int) $row['mark_time'];
+			// Get list of the unread topics - on forums tracking as the second step
+			// We don't take in account topics tracked before
+			$sql = 'SELECT t.topic_id, ft.mark_time
+				FROM ' . TOPICS_TABLE . ' t, ' . FORUMS_TRACK_TABLE . ' ft
+				WHERE t.forum_id = ft.forum_id
+					AND t.topic_last_post_time > ft.mark_time
+					AND ' . $db->sql_in_set('t.topic_id', $tracked_topics_list, true, true) . "
+					AND ft.user_id = $user_id
+				$sql_extra
+				ORDER BY t.topic_last_post_time DESC";
+			$result = $db->sql_query_limit($sql, ($sql_limit - $unread_list_count));
+
+			while ($row = $db->sql_fetchrow($result))
+			{
+				$unread_topics_list[$row['topic_id']] = (int) $row['mark_time'];
+			}
+			$db->sql_freeresult($result);
+
+			// Refresh the full list of the tracked topics and unread topics count
+			unset($tracked_topics_list);
+			$tracked_topics_list = array_merge(array_keys($unread_topics_list), array_keys($read_topics_list));
+			$unread_list_count = sizeof($unread_topics_list);
+
+			if ($unread_list_count < $sql_limit)
+			{
+				// List of the tracked forums (not ideal, hope the better way will be found)
+				// This list is to fetch later the forums user never read (fully) before
+				$sql = 'SELECT forum_id
+					FROM ' . FORUMS_TRACK_TABLE . "
+					WHERE user_id = $user_id";
+				$result = $db->sql_query($sql);
+
+				while ($row = $db->sql_fetchrow($result))
+				{
+					$tracked_forums_list[] = (int) $row['forum_id'];
+				}
+				$db->sql_freeresult($result);
+
+				// And the last step - find unread topics were not found before (that can mean a user has never read some forums)
+				$sql = 'SELECT t.topic_id
+					FROM ' . TOPICS_TABLE . ' t
+					WHERE t.topic_last_post_time > ' . (int) $user->data['user_lastmark'] . '
+						AND ' . $db->sql_in_set('t.topic_id', $tracked_topics_list, true, true) . '
+						AND ' . $db->sql_in_set('t.forum_id', $tracked_forums_list, true, true) . "
+					$sql_extra
+					ORDER BY t.topic_last_post_time DESC";
+				$result = $db->sql_query_limit($sql, ($sql_limit - $unread_list_count));
+
+				while ($row = $db->sql_fetchrow($result))
+				{
+					$unread_topics_list[$row['topic_id']] = (int) $user->data['user_lastmark'];
+				}
+				$db->sql_freeresult($result);
+			}
 		}
-		$db->sql_freeresult($result);
-
-		// Refresh the full list of the tracked topics
-		unset($tracked_topics_list);
-		$tracked_topics_list = array_merge(array_keys($unread_topics_list), array_keys($read_topics_list));
-
-		// And the last step - find unread topics were not found before (that can mean a user has never read some forums)
-		$sql = 'SELECT t.topic_id
-			FROM ' . TOPICS_TABLE . ' t
-			WHERE t.topic_last_post_time > ' . (int) $user->data['user_lastmark'] . '
-				AND ' . $db->sql_in_set('t.topic_id', $tracked_topics_list, true, true) . '
-				AND ' . $db->sql_in_set('t.forum_id', $tracked_forums_list, true, true) . "
-			$sql_extra
-			ORDER BY t.topic_last_post_time DESC";
-		$result = $db->sql_query_limit($sql, 1000);
-
-		while ($row = $db->sql_fetchrow($result))
-		{
-			$unread_topics_list[$row['topic_id']] = (int) $user->data['user_lastmark'];
-		}
-		$db->sql_freeresult($result);
 	}
 	else if ($config['load_anon_lastread'] || $user->data['is_registered'])
 	{