Most of the “microblog” posts I’m seeing are pretty short. I seem to remember the images being way too big, though. I made a custom ublock rule or something to make both the lemmy ones and them equally small thumbnails just big enough to decide if I want to load a full-sized one. It’s kept working for a year or something, I had forgotten it was there, but I guess it helps even more now.

Edit: Ah, found it. It’s a firefox/librewolf userContent.css thing. Maybe something similar could be an mbin user configurable option some day.

@-moz-document domain("fedia.io") {
    .figure-thumb { max-height:90px !important; max-width:160px !important; overflow: hidden; }
    .view-compact .entry figure { height:90px !important; width: 160px !important} 
}