If you have not changed your avatar since the migration, you might have a gigantic image for an avatar.
Discourse took images that were pretty compressed already in some cases and made them significantly larger? That's idiotic and directly bass-ackwards. Jeff, if you read this, do realise that you are fucking retarded.
Oh well, now my avatar is only wasting around 2.5KB (instead of 150KB before!) so I guess we can live with that.