jQuery AJAX vs. UpdatePanel

Don't move to UpdatePanels. After coming from jQuery, the drop in performance would be untenable. Especially on a page as complex as yours sounds.

If you have 2,000 lines of JavaScript code, the solution is to refactor that code. If you put 2,000 lines of C# code in one file, it would be difficult to maintain too. That would be difficult to manage effectively with any language or tool.

If you're using 3.5 SP1, you can use the ScriptManager's new script combining to separate your JavaScript into multiple files with no penalty. That way, you can logically partition your code just as you would with server side code.

Please don't put your self in that world of pain. Instead use UFRAME which is a lot faster and is implemented in jQuery.

Now, to manage those 2000 lines of Javascript code I recommend splitting the code in different files and set up your build process to join them using JSMin or Yahoo Compressor into chunks.

I don't know if there is a way to optimize UpdatePanels, but my company has found its performance to be pretty poor. jQuery is much much faster at doing pretty much anything.

There can be a lot of lag between the time when an UpdatePanel triggers an update and when the UpdatePanel actually updates the page.

The only reason we use UpdatePanels is because of the ease of development. Almost nothing needs to be done to make them work.