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.

Mark Jaquith

When your posts get a lot of comments, performance can be a concern. The generation of the comment HTML and the delivery of all that HTML can slow down your page loads. This plugin has pages load without comments, and then uses a secondary AJAX request to pull down the comments. Navigating through the pages of comments is also handled via AJAX. On my test install with 100 comments per page, the <code>onload</code> event fires 2x faster. The HTML is generated by the server 6x faster. The HTML downloads 3x faster. The uncompressed size of the HTML is reduced by a factor of 17.
Initial development of this plugin was commissioned by Google — many thanks!

AJAX Comment Loading

Loads comments with a secondary AJAX request, including comment paging. Speeds initial loading of the page.

Page Load Ajax vs AJAX Comment Loading