I had the same issue with Xitami login/logout being slow, but I fixed it! I was putting debug in to track it and my problem went away! I simply left some debug at the top that display a CHAR 255 (invisible char) and it works very fast now!!
Open the "login.php" in notepad and add the following line after:
$header_location = ( @preg_match('/Microsoft|WebSTAR|Xitami/', getenv('SERVER_SOFTWARE')) ) ? 'Refresh: 0; URL=' : 'Location: ';
echo "."; // FLC - FIXES SLOW LOGIN/LOGOUT WITH XITAMI
For the period, you can add a CHR 255, which is invisible. The period works also. If you have any questions, let me know.