Web sites were slowed down by mostly Server Sided code (code that dynamically generates the html before returning the page to the browser). MIcrosoft really crippled the web with their attempt to persist session state (retaining information gathered during the users visit to the site) by including an encrypted string hidden in the page, with all the session data (called ViewState).

To make websites more interactive, browsers now include an object used to post to web sites from scripting languages like Javascript. A standard used to incorporate this into web pages is called AJAX. Microsoft even messed this up, with their implementation using a component they called an update panel (a glorified div tag). The idea behind AJAX is that you send the minimum amount of information to a web server and get back only what data you need, then use Javascript to update your web page with the data. Microsofts idea was/is to send everything (full page post back), get the whole page back, grab the html content of the areas it cares to update and replaces the existing page with that content.

They essentially did their best to slow things down as much as possible, but avoid the page from appearing to reload.

Thankfully, with the help of Javascript libraries such as JQuery, Microsoft can be entirely bypassed for AJAX implementations of .Net based web applications. Of course, Java, PHP, Ruby On Rails and pretty much everything else is much better at implementing Ajax based client sided applications.

So in summary: Web applications are faster and more responsive than ever, thanks to less server sided page rendering and by not using Microsoft solutions.

/endgeekrant.