There are many Yola sites that perform well in the search engines, but this has to do with time and effort that is put into search engine optimization (SEO) and not the Sitebuilder itself.
Yola Sitebuilder provides areas for adding Google Webmaster verification code, title description and keywords meta tags, as well as ways to optimize your text and images.
Yola has also put together a great deal of documentation to help you with SEO.
You may also find this useful:
Adding website analytics
How can I edit my meta tags?
Measuring website traffic with analytics tools
How much traffic can my website handle?
Using Traffic Builder for better SEO