I think the Facebook "I don't want to see this" data is stored server-side, but the code that actually hides posts runs as client-side javascript. That would e

I think the Facebook "I don't want to see this" data is stored server-side, but the code that actually hides posts runs as client-side javascript. That would explain why the client spins so much loading/hiding posts you've hidden, and why the hidden-ness is persistent across browsers. I've gotten the impression from several accounts that, despite their prestige, Facebook's application code is often unbelievably janky, and this just confirms that.