I’m a big fan of WordPress, in fact I haven’t built a web platform with anything but WordPress in the last 5 years. Need an e-commerce website? You can do it with WordPress. Need a Craigslist type classifieds website? WordPress is there for you again.
With that being said not all WordPress websites are created equal and that is often because of the theme framework used by the website operator.
WHAT IS A WORDPRESS FRAMEWORK
If you are unfamiliar with WordPress frameworks in the most simply of terms they are barebone themes that are optimized for SEO, page load and other optimization purposes.
Several of the most popular WordPress frameworks include the awesome Genesis Theme and the equally cool Thematic framework.
Users choosing a framework should keep in mind that too many changes to the framework can hurt optimization. I tell clients that they should use the custom.css (or equally similar section) to change the look of their websites output without changing the actual structure of its templates.