diff --git includes/functions_content.php includes/functions_content.php
index ce70fb1..ebfbaf7 100644
--- includes/functions_content.php
+++ includes/functions_content.php
@@ -1213,8 +1213,20 @@ function get_username_string($mode, $user_id, $username, $username_colour = '',
 {
 	global $phpbb_root_path, $phpEx, $user, $auth;
 
-	$profile_url = '';
+	static $profile_cache;
+	static $profile_url_base;
+
+	if ($mode == 'profile' && isset($profile_cache[$user_id]))
+	{
+		// We don't cache 'no_profile' mode
+		return $profile_cache[$user_id];
+	}
+
 	$username_colour = ($username_colour) ? '#' . $username_colour : '';
+	if ($mode == 'colour')
+	{
+		return $username_colour;
+	}
 
 	if ($guest_username === false)
 	{
@@ -1225,64 +1237,66 @@ function get_username_string($mode, $user_id, $username, $username_colour = '',
 		$username = ($user_id && $user_id != ANONYMOUS) ? $username : ((!empty($guest_username)) ? $guest_username : $user->lang['GUEST']);
 	}
 
-	// Only show the link if not anonymous
-	if ($mode != 'no_profile' && $user_id && $user_id != ANONYMOUS)
+	if ($mode == 'username')
+	{
+		return $username;
+	}
+
+	if (!isset($profile_url_base))
 	{
-		// Do not show the link if the user is already logged in but do not have u_viewprofile permissions (relevant for bots mostly).
-		// For all others the link leads to a login page or the profile.
-		if ($user->data['user_id'] != ANONYMOUS && !$auth->acl_get('u_viewprofile'))
+		if ($user->data['user_id'] != ANONYMOUS && $auth->acl_get('u_viewprofile'))
 		{
-			$profile_url = '';
+			$profile_url_base = append_sid("{$phpbb_root_path}memberlist.$phpEx", 'mode=viewprofile');
 		}
 		else
 		{
-			$profile_url = ($custom_profile_url !== false) ? $custom_profile_url . '&u=' . (int) $user_id : append_sid("{$phpbb_root_path}memberlist.$phpEx", 'mode=viewprofile&u=' . (int) $user_id);
+			$profile_url_base = '';
 		}
 	}
+
+	// Only show the link if not anonymous
+	if ($mode != 'no_profile' && $user_id && $user_id != ANONYMOUS && $profile_url_base)
+	{
+		$profile_url = (($custom_profile_url !== false) ? $custom_profile_url : $profile_url_base) . '&u=' . (int) $user_id;
+	}
 	else
 	{
 		$profile_url = '';
 	}
 
-	switch ($mode)
-	{
-		case 'profile':
-			return $profile_url;
-		break;
-
-		case 'username':
-			return $username;
-		break;
 
-		case 'colour':
-			return $username_colour;
-		break;
+	if ($mode == 'profile')
+	{
+		return $profile_url;
+	}
 
-		case 'no_profile':
-		case 'full':
-		default:
+	// If we arive here mode is 'profile' or 'no_profile'
+	$tpl = '';
+	if (!$profile_url && !$username_colour)
+	{
+		$tpl = '{USERNAME}';
+	}
+	else if (!$profile_url && $username_colour)
+	{
+		$tpl = '<span style="color: {USERNAME_COLOUR};" class="username-coloured">{USERNAME}</span>';
+	}
+	else if ($profile_url && !$username_colour)
+	{
+		$tpl = '<a href="{PROFILE_URL}">{USERNAME}</a>';
+	}
+	else if ($profile_url && $username_colour)
+	{
+		$tpl = '<a href="{PROFILE_URL}" style="color: {USERNAME_COLOUR};" class="username-coloured">{USERNAME}</a>';
+	}
 
-			$tpl = '';
-			if (!$profile_url && !$username_colour)
-			{
-				$tpl = '{USERNAME}';
-			}
-			else if (!$profile_url && $username_colour)
-			{
-				$tpl = '<span style="color: {USERNAME_COLOUR};" class="username-coloured">{USERNAME}</span>';
-			}
-			else if ($profile_url && !$username_colour)
-			{
-				$tpl = '<a href="{PROFILE_URL}">{USERNAME}</a>';
-			}
-			else if ($profile_url && $username_colour)
-			{
-				$tpl = '<a href="{PROFILE_URL}" style="color: {USERNAME_COLOUR};" class="username-coloured">{USERNAME}</a>';
-			}
+	$profile = str_replace(array('{PROFILE_URL}', '{USERNAME_COLOUR}', '{USERNAME}'), array($profile_url, $username_colour, $username), $tpl);
 
-			return str_replace(array('{PROFILE_URL}', '{USERNAME_COLOUR}', '{USERNAME}'), array($profile_url, $username_colour, $username), $tpl);
-		break;
+	if ($mode != 'no_profile')
+	{
+		$profile_cache[$user_id] = $profile;
 	}
+
+	return $profile;
 }
 
 /**