I forget what that thread was called recently where a few users wanted to disable images because of low bandwidth and data caps, the new firefox version has that ability
I believe it was this thread: 
do you have post numbers?
I thought there would be a bunch, but I did a search for the word "images" and only found one or two relevent posts: 
Thats not the one i was looking for, there was a thread or posts about someone wanting to not load images because of their slow connection or low bandwidth cap (or both?)
Winner, winner, chicken dinner!
thank you 
Excellent! 
When shall I show up? I bring my own bbq sauce. 
Friday, May 13th. (My friend Jason should be in town.) We'll have plenty of barbecue chicken and pony.
You wouldn’t want to eat me. My flesh is contagious and not very tasty either. 
Might bring alone my friend Freddy. He says he knows your Jason.
I think this is deliberate obfuscation, your just trying to save your own skin
So that’s why he was mumbling something about having a score to settle!
When Jason and Freddie get together, everyone wins! 
This is what it does …
“Image loading control
Firefox for Android 45 features a new option to control when images get loaded in the browser. Set to always load images by default, it can be set to only load images over Wi-Fi, or never.”
Not very helpful as the OP in other thread had bandwidth issues as images are reloading each time he loads up a thread…