Pronto is a rather awesome little jQuery plugin I’ve just implemented in my site. In the words of the plugin’s author, Ben Plum:
Using a “partial page load” technique, Pronto reduces the over all server load and font-end render time by only updating pieces of a page instead of the entire document.
The initial setup can be a bit fiddly, but I’ve found it to be pretty smooth sailing once it’s all set up. Well worth checking out.