Do you mean the user avatars on the screen News Feed » Activities, or something else? They are loading pretty instantly on my phone.
Or do you mean photos attached to individual activities, when you open the activity? Those are loading instantly on my side too. And as for adding photos to own activities, the mosaic with photos avaiable on the phone pops up instantly too on my phone, with no delay. It also does not use any web connection.
Generally it sounds rather like your phone may have some performance issues, or perhaps it throttles the performance due to battery optimizing options, or you have too many running apps on it.
