Facebook doesn't work

Hi, got big problem here

The facebook app didn't work well on my iPhone , when I logged in all just slow & keep loading ,also can't see all images from others post, the notification and the menu profil bar .

I try to log in trought the browser (safari) it also didn't work well , every facebook site I visit all just slow and slow - - , other site is fine and fast ,also the others app like Games,YouTube,etc .

then I use my sister's iPhone and try log in to facebook ,it fast as flash , then I told to my sister try to log in her facebook account using my iphone , the Slow affected to my sister's facebook account . I also have logged in my facebook account using my laptop and android ,both worked fine and fast.

I confused what wrong just happened with my iPhone . Any suggestions?