Loading <!--nextpage--> post with Ajax

Here's the case I got: I've setup post pagination for my website and everything works well. Except one thing - on every new page request all the resources are loaded again. This makes the website loading slow and breaks the user experience.

What I want to do is to load the content of the separate pages by ajax and replace them. The prev and next rel tags are setup so this won't be a problem for search engines to understand my content because they'll follow the tags.(correct me if I'm wrong)

However, I cannot find a way to do it because the post pages do not have a separate entry in the database. Any ideas how I can accomplish this?

I'm using tag to separate my posts into pages.