Jacob N. Breetvelt

The purpose of this plugin is to minimize page load time and resource usage by updating the page title and content only rather then reloading the entire webpage. 
The new contents and titles are fetched by ajax calls.
Restriction: 
As the rest of the page like header including all styles and scripts, footer and sidebars are not affected, you should only use this to switch between pages with the same overall layout and requirements.
You can enter shortcodes in the page content that will show up as a button or a text link. 
When activating the link, the pages title and content will be replaced by the title and content of the specified page.
There are four possible independant arguments to the shortcode: 
– page (required). This can be the page title or the page id. 
– text (optional). The button text or textlink text. 
– title-elm (optional). The title element id or class if it is not the default as entered on the settings page. 
– content-elm (optional). The content element id or class if not default.
Examples: [pla page=”Tet page”] [pla page=”5″ text=”Go to the testpage”] [pla page=”My Page” content-elm=”#my-div”]

Page Load Ajax

This plugin enables the use of shortcodes that create links to replace the current page content with the content of another page.

AspieSoft

Easily lazy load another page simply by adding a shortcode with its url.
The 2nd page wont load until the user scrolls to the bottom, than an ajax request is sent to get the page content. 
This can help speed up large pages on your site, by not loading the stuff users don’t see until they scroll down closer to the bottom.

AspieSoft Ajax Load Page

Easily lazy load another page simply by adding a shortcode with its url.

Page Load Ajax vs AspieSoft Ajax Load Page