This is a start on a collection of resources about speeding up hosted wordpress sites. Here’a part of that article’s information:
Remove Unnecessary PHP Executions and DB Access
Those wonderful themes that we all choose are often loaded with PHP bloat. Some theme’s such as my own Rapid Access were designed specifically for speed. But others are designed mainly for looks (I’m not going to name any names). But all of them have some very generic code in them to allow them to be easily installed on any blog.