I have just got this message, too, and it is very annoying when making a bot assisted manual spelling correction on several pages. The bot will namely not display the next page to correct until the lag is over. That's not the bot who is waiting and can't work, but me. Although we have put_async to do the human work faster and let the bot do the rest while we do something more useful, it is useless when my own work is stopped for five minutes.