I've been on a crappy mobile connection while traveling and have been more mindful of bandwidth usage. I've noticed the following:

Nostr seems to use an order of magnitude more bandwidth than X, despite me spending far more screen time on X.

I suspect this is because X controls the delivery of multimedia content and thus ensures it's downsampled and optimally compressed for mobile app rendering.

Whereas nostr media is hosted and delivered at the original raw file size at which it was uploaded.