We did try some solutions, but It still didn’t work. This issue may be caused by Access-Control-Allow-Origin error; the problem comes from your server. Please help us try to config on your server because we don’t have permission. You can find the way here: http://stackoverflow.com/questions/41036415/cors-with-php-wordpress. We are so sorry for the unwanted inconvenience
BTW: We just test and don’t do nothing related to your website speed