Why is pagination so resource-expensive?

Question

It's one of those things that seems to have an odd curve where the more I think about it, the more it makes sense. To a certain extent, of course. And then it doesn't make sense to me at all.

Care to enlighten me?

Answer 1

Because in most cases you've got to sort your results first. For example, when you search on Google, you can view only up to 100 pages of results. They don't bother sorting by page-rank beyond 1000 websites for given keyword (or combination of keywords).

Pagination is fast. Sorting is slow.