With all the innovation taking place in the jQuery project, one of the easiest ways to improve the performance of your web site is to simply use the latest version of jQuery. Every release of the library introduces optimizations and bug fixes, and most of the time upgrading involves only changing a script tag.
You can even include jQuery directly from Google’s servers, which provide free CDN hosting for a number of JavaScript libraries.
<!-- Include a specific version of jQuery -->
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.6.1/jquery.min.js"></script>
<!-- Include the latest version in the 1.6 branch -->
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.6/jquery.min.js"></script>The latter example will include the latest 1.6.x version automatically as it becomes available, but as pointed out on css-tricks, it is cached only for an hour, so you better not use it in production environments.