diff --git a/phpBB/docs/CHANGELOG.html b/phpBB/docs/CHANGELOG.html
index f4a79411d1..70026d724b 100644
--- a/phpBB/docs/CHANGELOG.html
+++ b/phpBB/docs/CHANGELOG.html
@@ -186,6 +186,7 @@
 		<li>[Change] Add confirmation for deactivating language packs (Patch by leviatan21)</li>
 		<li>[Change] Add confirm-box when deleting permissions (Bug #13673 - Patch by nickvergessen)</li>
 		<li>[Change] Add pagination for icons and smilies in the ACP and smilies in the smiley popup</li>
+		<li>[Change] Cache get_username_string() function calls on viewtopic.</li>
 		<li>[Feature] Add language selection on the registration terms page (Bug #15085 - Patch by leviatan21)</li>
 		<li>[Feature] Backported 3.2 captcha plugins.</li>
 		<li>[Feature] Introduced new ACM plugins:
diff --git a/phpBB/viewtopic.php b/phpBB/viewtopic.php
index 0ddf8603fc..f3f6923381 100644
--- a/phpBB/viewtopic.php
+++ b/phpBB/viewtopic.php
@@ -1116,6 +1116,11 @@ while ($row = $db->sql_fetchrow($result))
 				'yim'			=> ($row['user_yim']) ? 'http://edit.yahoo.com/config/send_webmesg?.target=' . urlencode($row['user_yim']) . '&amp;.src=pg' : '',
 				'jabber'		=> ($row['user_jabber'] && $auth->acl_get('u_sendim')) ? append_sid("{$phpbb_root_path}memberlist.$phpEx", "mode=contact&amp;action=jabber&amp;u=$poster_id") : '',
 				'search'		=> ($auth->acl_get('u_search')) ? append_sid("{$phpbb_root_path}search.$phpEx", "author_id=$poster_id&amp;sr=posts") : '',
+
+				'author_full'		=> get_username_string('full', $poster_id, $row['username'], $row['user_colour']),
+				'author_colour'		=> get_username_string('colour', $poster_id, $row['username'], $row['user_colour']),
+				'author_username'	=> get_username_string('username', $poster_id, $row['username'], $row['user_colour']),
+				'author_profile'	=> get_username_string('profile', $poster_id, $row['username'], $row['user_colour']),
 			);
 
 			get_user_rank($row['user_rank'], $row['user_posts'], $user_cache[$poster_id]['rank_title'], $user_cache[$poster_id]['rank_image'], $user_cache[$poster_id]['rank_image_src']);
@@ -1434,10 +1439,10 @@ for ($i = 0, $end = sizeof($post_list); $i < $end; ++$i)
 
 	//
 	$postrow = array(
-		'POST_AUTHOR_FULL'		=> get_username_string('full', $poster_id, $row['username'], $row['user_colour'], $row['post_username']),
-		'POST_AUTHOR_COLOUR'	=> get_username_string('colour', $poster_id, $row['username'], $row['user_colour'], $row['post_username']),
-		'POST_AUTHOR'			=> get_username_string('username', $poster_id, $row['username'], $row['user_colour'], $row['post_username']),
-		'U_POST_AUTHOR'			=> get_username_string('profile', $poster_id, $row['username'], $row['user_colour'], $row['post_username']),
+		'POST_AUTHOR_FULL'		=> ($poster_id != ANONYMOUS) ? $user_cache[$poster_id]['author_full'] : get_username_string('full', $poster_id, $row['username'], $row['user_colour'], $row['post_username']),
+		'POST_AUTHOR_COLOUR'	=> ($poster_id != ANONYMOUS) ? $user_cache[$poster_id]['author_colour'] : get_username_string('colour', $poster_id, $row['username'], $row['user_colour'], $row['post_username']),
+		'POST_AUTHOR'			=> ($poster_id != ANONYMOUS) ? $user_cache[$poster_id]['author_username'] : get_username_string('username', $poster_id, $row['username'], $row['user_colour'], $row['post_username']),
+		'U_POST_AUTHOR'			=> ($poster_id != ANONYMOUS) ? $user_cache[$poster_id]['author_profile'] : get_username_string('profile', $poster_id, $row['username'], $row['user_colour'], $row['post_username']),
 
 		'RANK_TITLE'		=> $user_cache[$poster_id]['rank_title'],
 		'RANK_IMG'			=> $user_cache[$poster_id]['rank_image'],