The site runs fine on my end too.  There is a possibility that you're cache memory is full since the cache memory being full slows down your internet browsing.   If you do not how how to clear you cahe or cookies, you can find the procedure here : https://support.google.com/accounts/answer/32050
 while you can use this guide when you wanted to clear the cache of your mobile phone : https://timesofindia.indiatimes.com/gadgets-news/how-to-clear-cache-on-your-android-phone-and-why-it-is-important/articleshow/105217612.cms