How to Optimize a SharePoint Server 2007 Web Content Management Site for Performance
We had a technical discussion about enhancing the performance of the MOSS , the discussion contains optimizing the core.css and core.js also to optimize the menu by using alternatives menus and integrate it with sitemap provider, yet the guys did great effort to optimize a MOSS site from 900K to 200K and they are still working to optimize more and more, I’ll share the final results after validating the optimized components. Also MSDN has a useful article about MOSS optimization please check it
here