Q: Does anyone know how to Eliminate render-blocking JavaScript and CSS in above-the-fold content

Read this :

https://developers.google.com/speed/docs/insights/BlockingJS

Make JavaScript Asynchronous

By default JavaScript blocks DOM construction and thus delays the time to first render. To prevent JavaScript from blocking the parser we recommend using the HTML async attribute on external scripts. For example:

<script async src="my.js">

See Parser Blocking vs. Asynchronous JavaScript to learn more about asynchronous scripts. Note that asynchronous scripts are not guaranteed to execute in specified order and should not use document.write. Scripts that depend on execution order or need to access or modify the DOM or CSSOM of the page may need to be rewritten to account for these constraints.

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To do that in iWeb, open the published webpages and add async to each javascript link at the top of the code :

<script type="text/javascript" async src="Scripts/iWebSite.js"></script>
<script type="text/javascript" async src="Scripts/Widgets/SharedResources/WidgetCommon.js"></script>
<script type="text/javascript" async src="Scripts/Widgets/PHPInclude/Paste.js"></script>
<script type="text/javascript" async src="Scripts/iWebImage.js"></script>
<script type="text/javascript" async src="Home_files/Home.js"></script>

Most likely you're posting the question in the wrong forum, but with or without iWeb you now know what to do.

What you want, and what Google describes, cannot be done in iWeb.

So you have to do it after publishing the pages.

iWeb SEOTool has a forum :

http://www.ragesw.com/forums/index.php?/forum/22-seo-software-discussions/