Yes, I can't see how it can't be the pictures, really. Even tiny pictures are so much more data than lines and lines and lines of text. If the servers are struggling, it's nuts to be allowing people to post pictures (given that they clearly can't afford to upgrade the server provision). And the SODDING GIANT banner with the gurning baby and woman with grey bump. Surely that has an impact.
To my shame, I posted a picture the other day. I was a little bit tipsy and I thought, well, let's try it. But it's interesting. Actually, not being able to post a picture makes you work harder to make your post funny/interesting/descriptive. The post I posted with a picture was really extremely dull because the picture had done the talking for me.