> I don't think something like checking whether a comment is member of the list of hidden items by a user would really add workload of any significance.
I don't think so either. My comment was that "all the work is done on the servers". For the whole app. That is looking at all of the cost in aggregate (every interaction requires a http request, and requires throttling, session handling, authentication, html page generation, and so on....).
> Does that not lead to an awful lot of traffic sometimes? (I'm imagining a version of News that would transmit all submitted content to let the client do the sorting and searching instead of doing it on the server.)
Sure if you fetch all data unsorted, but I wasn't suggesting (or at least thinking) anything like that. I was just suggesting the html creation and many interactions that currently represent at least half if not most of the workload the server operations are currently doing.